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  1. <html><head><meta charset="utf-8" /></head><body>
  2. <p>湖南省常德市2019-2020学年高一数学上学期第一次月考试题(含解析)</p>
  3. <p>一、选择题(本大题12小题,每小题5分,共60分)</p>
  4. <p>1. 若sinα>0,且cosα<0,则角α是( )</p>
  5. <p>A. 第一象限角B. 第二象限角C. 第三象限角D. 第四象限角</p>
  6. <p>【答案】B</p>
  7. <p>【解析】</p>
  8. <p>试题分析:直接由三角函数的象限符号取交集得答案.</p>
  9. <p>解:由sinα>0,可得α为第一、第二及y轴正半轴上的角;</p>
  10. <p>由cosα<0,可得α为第二、第三及x轴负半轴上的角.</p>
  11. <p>∴取交集可得,α是第二象限角.</p>
  12. <p>故选B.</p>
  13. <p>考点:三角函数值的符号.</p>
  14. <p>2.函数<img src="files/image1.png" width="147px" height="45px" data-latex="$$" /><img src="files/image2.png" width="14px" height="19px" data-latex="$$" />最小正周期为(   )</p>
  15. <p>A. <img src="files/image3.png" width="16px" height="42px" data-latex="$$" />B. <img src="files/image4.png" width="17px" height="41px" data-latex="$$" />C. <img src="files/image5.png" width="15px" height="15px" data-latex="$$" />D. <img src="files/image6.png" width="24px" height="19px" data-latex="$$" /></p>
  16. <p>【答案】B</p>
  17. <p>【解析】</p>
  18. <p>【分析】</p>
  19. <p>根据正切函数的周期公式<img src="files/image7.png" width="44px" height="41px" data-latex="$$" />进行计算即可.</p>
  20. <p>【详解】函数<img src="files/image1.png" width="147px" height="45px" data-latex="$$" />的最小正周期为:<img src="files/image8.png" width="72px" height="41px" data-latex="$$" />,</p>
  21. <p>故选:B.</p>
  22. <p>【点睛】本题考查正切函数的最小正周期,熟记公式是解题的关键,属于基础题.</p>
  23. <p>3.已知A={第一象限角},B={锐角},C={小于90°的角},那么A、B、C关系是( )</p>
  24. <p>A. B=A∩CB. B∪C=CC. A<img src="files/image9.png" width="17px" height="19px" data-latex="$$" />CD. A=B=C</p>
  25. <p>【答案】B</p>
  26. <p>【解析】</p>
  27. <p>【分析】</p>
  28. <p>由集合A,B,C,求出B与C的并集,判断A与C的包含关系,以及A,B,C三者之间的关系即可.</p>
  29. <p>【详解】由题B<img src="files/image10.png" width="16px" height="16px" data-latex="$$" />A,</p>
  30. <p>∵A={第一象限角},B={锐角},C={小于90°的角},</p>
  31. <p>∴B∪C={小于90°的角}=C,即B<img src="files/image10.png" width="16px" height="16px" data-latex="$$" />C,</p>
  32. <p>则B不一定等于A∩C,A不一定是C的真子集,三集合不一定相等,</p>
  33. <p>故选B.</p>
  34. <p>【点睛】此题考查了集合间的基本关系及运算,熟练掌握象限角,锐角,以及小于90°的角表示的意义是解本题的关键,是易错题</p>
  35. <p>4.化简:<img src="files/image11.png" width="109px" height="23px" data-latex="$$" />(   )</p>
  36. <p>A. <img src="files/image12.png" width="14px" height="23px" data-latex="$$" />B. <img src="files/image13.png" width="25px" height="22px" data-latex="$$" />C. <img src="files/image14.png" width="35px" height="21px" data-latex="$$" />D. <img src="files/image15.png" width="43px" height="21px" data-latex="$$" /></p>
  37. <p>【答案】A</p>
  38. <p>【解析】</p>
  39. <p>【分析】</p>
  40. <p>根据平面向量减法法则和相反向量的意义计算即可.</p>
  41. <p>【详解】<img src="files/image16.png" width="309px" height="25px" data-latex="$$" />,</p>
  42. <p>故选:A.</p>
  43. <p>【点睛】本题主要考查平面向量减法的三角形法则,属于基础题.</p>
  44. <p>5.在ΔABC中,若<img src="files/image17.png" width="199px" height="32px" data-latex="$$" /> ,则<img src="files/image18.png" width="55px" height="24px" data-latex="$$" />=( )</p>
  45. <p>A. 6B. 4C. -6D. -4</p>
  46. <p>【答案】C</p>
  47. <p>【解析】</p>
  48. <p>【分析】</p>
  49. <p>向量的点乘,<img src="files/image19.png" width="233px" height="32px" data-latex="$$" /></p>
  50. <p>【详解】<img src="files/image20.png" width="399px" height="41px" data-latex="$$" />,选C.</p>
  51. <p>【点睛】向量的点乘,需要注意后面乘的是两向量的夹角的余弦值,本题如果直接计算的话,<img src="files/image21.png" width="61px" height="24px" data-latex="$$" />的夹角为∠BAC的补角</p>
  52. <p>6.已知向量<img src="files/image22.png" width="61px" height="27px" data-latex="$$" />,向量<img src="files/image23.png" width="72px" height="28px" data-latex="$$" />,则向量<img src="files/image24.png" width="13px" height="19px" data-latex="$$" />在向量<img src="files/image25.png" width="15px" height="23px" data-latex="$$" />方向上的投影为( )</p>
  53. <p>A. <img src="files/image26.png" width="20px" height="16px" data-latex="$$" />B. <img src="files/image27.png" width="20px" height="17px" data-latex="$$" />C. <img src="files/image28.png" width="12px" height="17px" data-latex="$$" />D. <img src="files/image29.png" width="13px" height="17px" data-latex="$$" /></p>
  54. <p>【答案】B</p>
  55. <p>【解析】</p>
  56. <p>由题意可得:<img src="files/image30.png" width="303px" height="36px" data-latex="$$" /> ,</p>
  57. <p>则:向量<img src="files/image24.png" width="13px" height="19px" data-latex="$$" />在向量<img src="files/image25.png" width="15px" height="23px" data-latex="$$" />方向上<img src="files/image2.png" width="14px" height="19px" data-latex="$$" />投影为<img src="files/image31.png" width="189px" height="55px" data-latex="$$" /> .</p>
  58. <p>本题选择B选项.</p>
  59. <p>点睛:在向量数量积的几何意义中,投影是一个数量,不是向量.设向量a,b的夹角为θ,当θ为锐角时,投影为正值;当θ为钝角时,投影为负值;当θ为直角时,投影为0;</p>
  60. <p>7.已知<img src="files/image32.png" width="40px" height="32px" data-latex="$$" />,<img src="files/image33.png" width="41px" height="32px" data-latex="$$" />,且<img src="files/image34.png" width="13px" height="23px" data-latex="$$" />与<img src="files/image35.png" width="13px" height="23px" data-latex="$$" />夹角为<img src="files/image36.png" width="27px" height="19px" data-latex="$$" />,则<img src="files/image37.png" width="63px" height="32px" data-latex="$$" />等于(   )</p>
  61. <p>A. 1B. 3C. <img src="files/image38.png" width="47px" height="24px" data-latex="$$" />D. <img src="files/image39.png" width="47px" height="24px" data-latex="$$" /></p>
  62. <p>【答案】B</p>
  63. <p>【解析】</p>
  64. <p>【分析】</p>
  65. <p>先根据平面向量的运算法则对式子展开,然后根据平面向量的数量积公式计算即可.</p>
  66. <p>【详解】因为<img src="files/image32.png" width="40px" height="32px" data-latex="$$" />,<img src="files/image33.png" width="41px" height="32px" data-latex="$$" />,且<img src="files/image34.png" width="13px" height="23px" data-latex="$$" />与<img src="files/image35.png" width="13px" height="23px" data-latex="$$" />夹角为<img src="files/image36.png" width="27px" height="19px" data-latex="$$" />,</p>
  67. <p>所以<img src="files/image40.png" width="383px" height="35px" data-latex="$$" />.</p>
  68. <p>故选:B.</p>
  69. <p>【点睛】本题主要考查平面向量的数量积的计算,属于基础题.</p>
  70. <p>8.函数<img src="files/image41.png" width="112px" height="45px" data-latex="$$" />的图象 ( )</p>
  71. <p>A. 关于点<img src="files/image42.png" width="48px" height="45px" data-latex="$$" />对称B. 关于直线<img src="files/image43.png" width="42px" height="42px" data-latex="$$" />对称</p>
  72. <p>C. 关于点<img src="files/image44.png" width="48px" height="45px" data-latex="$$" />对称D. 关于直线<img src="files/image45.png" width="41px" height="41px" data-latex="$$" />对称</p>
  73. <p>【答案】A</p>
  74. <p>【解析】</p>
  75. <p>【分析】</p>
  76. <p>分别求出函数<img src="files/image41.png" width="112px" height="45px" data-latex="$$" />的对称中心坐标和对称轴方程,然后对<img src="files/image46.png" width="13px" height="19px" data-latex="$$" />赋整数值得出结果.</p>
  77. <p>【详解】对于函数<img src="files/image41.png" width="112px" height="45px" data-latex="$$" />,令<img src="files/image47.png" width="133px" height="41px" data-latex="$$" />,得<img src="files/image48.png" width="77px" height="41px" data-latex="$$" />,<img src="files/image49.png" width="38px" height="19px" data-latex="$$" />,</p>
  78. <p>令<img src="files/image50.png" width="160px" height="41px" data-latex="$$" />,得<img src="files/image51.png" width="81px" height="41px" data-latex="$$" />,<img src="files/image49.png" width="38px" height="19px" data-latex="$$" />,</p>
  79. <p>所以,函数<img src="files/image41.png" width="112px" height="45px" data-latex="$$" />的图象的对称中心坐标为<img src="files/image52.png" width="135px" height="45px" data-latex="$$" />,对称轴为直线<img src="files/image53.png" width="132px" height="41px" data-latex="$$" />,</p>
  80. <p>令<img src="files/image54.png" width="35px" height="19px" data-latex="$$" />,可知函数<img src="files/image41.png" width="112px" height="45px" data-latex="$$" />图象的一个对称中心坐标为<img src="files/image42.png" width="48px" height="45px" data-latex="$$" />,故选A.</p>
  81. <p>【点睛】本题考查三角函数的对称中心和对称轴方程,一般先求出对称中心坐标和对称轴方程通式,然后通过赋值法得到,考查计算能力,属于基础题.</p>
  82. <p>9.函数<img src="files/image55.png" width="120px" height="45px" data-latex="$$" /><img src="files/image2.png" width="14px" height="19px" data-latex="$$" />单调递增区间是( )</p>
  83. <p>A. <img src="files/image56.png" width="179px" height="45px" data-latex="$$" />B. <img src="files/image57.png" width="188px" height="45px" data-latex="$$" /></p>
  84. <p>C. <img src="files/image58.png" width="167px" height="45px" data-latex="$$" />D. <img src="files/image59.png" width="169px" height="45px" data-latex="$$" /></p>
  85. <p>【答案】B</p>
  86. <p>【解析】</p>
  87. <p><img src="files/image60.png" width="224px" height="45px" data-latex="$$" />.</p>
  88. <p>则<img src="files/image61.png" width="119px" height="45px" data-latex="$$" />的单调减区间即为函数<img src="files/image62.png" width="119px" height="45px" data-latex="$$" />的单调递增区间.</p>
  89. <p>即<img src="files/image63.png" width="233px" height="41px" data-latex="$$" />.</p>
  90. <p>解得<img src="files/image64.png" width="188px" height="45px" data-latex="$$" /></p>
  91. <p>故选B.</p>
  92. <p>10.要得到函数<img src="files/image65.png" width="102px" height="41px" data-latex="$$" />的图象,只需将<img src="files/image66.png" width="102px" height="42px" data-latex="$$" />图象上的所有点( )</p>
  93. <p>A. 向左平行移动<img src="files/image67.png" width="15px" height="37px" data-latex="$$" />个单位长度B. 向右平行移动<img src="files/image67.png" width="15px" height="37px" data-latex="$$" />个单位长度</p>
  94. <p>C<img src="files/image68.png" width="3px" height="9px" data-latex="$$" /> 向左平行移动<img src="files/image69.png" width="20px" height="37px" data-latex="$$" />个单位长度D. 向右平行移动<img src="files/image69.png" width="20px" height="37px" data-latex="$$" />个单位长度</p>
  95. <p>【答案】D</p>
  96. <p>【解析】</p>
  97. <p>试题分析:<img src="files/image70.png" width="479px" height="48px" data-latex="$$" />,向右平移<img src="files/image69.png" width="20px" height="37px" data-latex="$$" />个单位得<img src="files/image71.png" width="111px" height="45px" data-latex="$$" />.选D.</p>
  98. <p>考点:三角函数图像变换</p>
  99. <p>【思路点睛】三角函数的图象变换,提倡“先平移,后伸缩”,但“先伸缩,后平移”也常出现在题目中,所以也必须熟练掌握.无论是哪种变形,切记每一个变换总是对字母x而言. 函数y=Asin(ωx+φ),x∈R是奇函数⇔φ=kπ(k∈Z);函数y=Asin(ωx+φ),x∈R是偶函数⇔φ=kπ+(k∈Z);函数y=Acos(ωx+φ),x∈R是奇函数⇔φ=kπ+(k∈Z);函数y=Acos(ωx+φ),x∈R是偶函数⇔φ=kπ(k∈Z).</p>
  100. <p>11.已知函数<img src="files/image72.png" width="93px" height="41px" data-latex="$$" />的定义域为<img src="files/image73.png" width="36px" height="22px" data-latex="$$" />,值域为<img src="files/image74.png" width="44px" height="21px" data-latex="$$" />,则<img src="files/image75.png" width="35px" height="19px" data-latex="$$" />的值不可能是( )</p>
  101. <p>A. <img src="files/image76.png" width="27px" height="41px" data-latex="$$" />B. <img src="files/image6.png" width="24px" height="19px" data-latex="$$" />C. <img src="files/image77.png" width="25px" height="41px" data-latex="$$" />D. <img src="files/image78.png" width="32px" height="41px" data-latex="$$" /></p>
  102. <p>【答案】D</p>
  103. <p>【解析】</p>
  104. <p>【详解】<img src="files/image72.png" width="93px" height="41px" data-latex="$$" />的周期为<img src="files/image79.png" width="21px" height="17px" data-latex="$$" />,<img src="files/image75.png" width="35px" height="19px" data-latex="$$" />不可能超过一个周期,如果超过一个周期值域为<img src="files/image80.png" width="46px" height="21px" data-latex="$$" />, <img src="files/image81.png" width="68px" height="42px" data-latex="$$" />,所以<img src="files/image75.png" width="35px" height="19px" data-latex="$$" />的值不可能是<img src="files/image78.png" width="32px" height="41px" data-latex="$$" /></p>
  105. <p>12.函数y=Asin(ωx+φ)(A>0,ω>0)的部分图象如图所示,则f(1)+f(2)+f(3)+<img src="files/image82.png" width="19px" height="10px" data-latex="$$" />+f(11)的值等于</p>
  106. <p><img src="files/image83.png" width="155px" height="102px" /></p>
  107. <p>A. 2B. <img src="files/image84.png" width="48px" height="23px" data-latex="$$" />C. <img src="files/image85.png" width="56px" height="23px" data-latex="$$" />D. <img src="files/image86.png" width="64px" height="23px" data-latex="$$" /></p>
  108. <p>【答案】C</p>
  109. <p>【解析】</p>
  110. <p>由图可知,<img src="files/image87.png" width="40px" height="17px" data-latex="$$" />,函数的周期为<img src="files/image88.png" width="79px" height="41px" data-latex="$$" />所以<img src="files/image89.png" width="44px" height="41px" data-latex="$$" />.φ=<img src="files/image28.png" width="12px" height="17px" data-latex="$$" />.所以<img src="files/image90.png" width="105px" height="41px" data-latex="$$" />.所<img src="files/image91.png" width="36px" height="27px" data-latex="$$" />=<img src="files/image92.png" width="231px" height="28px" data-latex="$$" />=<img src="files/image93.png" width="119px" height="28px" data-latex="$$" />=<img src="files/image94.png" width="51px" height="27px" data-latex="$$" />=<img src="files/image95.png" width="73px" height="28px" data-latex="$$" />=<img src="files/image96.png" width="21px" height="17px" data-latex="$$" /></p>
  111. <p><img src="files/image97.png" width="44px" height="27px" data-latex="$$" />=<img src="files/image98.png" width="72px" height="28px" data-latex="$$" />=<img src="files/image28.png" width="12px" height="17px" data-latex="$$" />.所以<img src="files/image99.png" width="277px" height="28px" data-latex="$$" />.故选C.</p>
  112. <p>二、填空题(本大题4小题,每小题5分,共20分)</p>
  113. <p>13.已知<img src="files/image100.png" width="59px" height="19px" data-latex="$$" />,则<img src="files/image101.png" width="112px" height="29px" data-latex="$$" />_______</p>
  114. <p>【答案】<img src="files/image102.png" width="14px" height="42px" data-latex="$$" /></p>
  115. <p>【解析】</p>
  116. <p>【分析】</p>
  117. <p>将<img src="files/image103.png" width="99px" height="29px" data-latex="$$" />展开,然后分子分母同时除以<img src="files/image104.png" width="45px" height="21px" data-latex="$$" />,得到一个关于<img src="files/image105.png" width="39px" height="17px" data-latex="$$" />的式子,代值计算即可.</p>
  118. <p>【详解】<img src="files/image103.png" width="99px" height="29px" data-latex="$$" /></p>
  119. <p><img src="files/image106.png" width="203px" height="21px" data-latex="$$" /> </p>
  120. <p><img src="files/image107.png" width="137px" height="44px" data-latex="$$" /> </p>
  121. <p><img src="files/image108.png" width="69px" height="41px" data-latex="$$" /> </p>
  122. <p><img src="files/image109.png" width="26px" height="42px" data-latex="$$" /> .</p>
  123. <p>故答案为:<img src="files/image102.png" width="14px" height="42px" data-latex="$$" /> .</p>
  124. <p>【点睛】本题考查同角三角函数的基本关系以及“弦化切”的应用,属于常考题.</p>
  125. <p>14.函数<img src="files/image110.png" width="143px" height="27px" data-latex="$$" />,若<img src="files/image111.png" width="61px" height="27px" data-latex="$$" />,则<img src="files/image112.png" width="60px" height="27px" data-latex="$$" />____</p>
  126. <p>【答案】<img src="files/image113.png" width="21px" height="19px" data-latex="$$" /></p>
  127. <p>【解析】</p>
  128. <p>试题分析:<img src="files/image114.png" width="297px" height="27px" data-latex="$$" />,<img src="files/image115.png" width="244px" height="27px" data-latex="$$" /></p>
  129. <p>考点:函数求值</p>
  130. <p>15.已知一个扇形周长为4,面积为1,则其中心角等于 (弧度).</p>
  131. <p>【答案】2</p>
  132. <p>【解析】</p>
  133. <p>试题分析:由周长为4,可得<img src="files/image116.png" width="64px" height="19px" data-latex="$$" />,又由面积为1,可得<img src="files/image117.png" width="49px" height="41px" data-latex="$$" />,解得<img src="files/image118.png" width="68px" height="21px" data-latex="$$" />,∴<img src="files/image119.png" width="65px" height="41px" data-latex="$$" />.</p>
  134. <p>考点:弧度制下的扇形的相关公式.</p>
  135. <p>16.已知向量<img src="files/image120.png" width="109px" height="28px" data-latex="$$" />,<img src="files/image121.png" width="69px" height="25px" data-latex="$$" />,则<img src="files/image122.png" width="40px" height="35px" data-latex="$$" />的最大值为_________</p>
  136. <p>【答案】3</p>
  137. <p>【解析】</p>
  138. <p><img src="files/image123.png" width="10px" height="18px" data-latex="$$" />分析】</p>
  139. <p>对<img src="files/image122.png" width="40px" height="35px" data-latex="$$" />先平方再开方,然后利用辅助角公式及三角函数的有界性计算即可.</p>
  140. <p>【详解】<img src="files/image124.png" width="15px" height="13px" data-latex="$$" /><img src="files/image125.png" width="45px" height="37px" data-latex="$$" /><img src="files/image126.png" width="64px" height="25px" data-latex="$$" /><img src="files/image127.png" width="107px" height="25px" data-latex="$$" /><img src="files/image128.png" width="156px" height="25px" data-latex="$$" /><img src="files/image129.png" width="115px" height="41px" data-latex="$$" />,</p>
  141. <p>又<img src="files/image130.png" width="123px" height="41px" data-latex="$$" />,</p>
  142. <p><img src="files/image131.png" width="15px" height="13px" data-latex="$$" /><img src="files/image132.png" width="91px" height="37px" data-latex="$$" />,</p>
  143. <p><img src="files/image131.png" width="15px" height="13px" data-latex="$$" /><img src="files/image133.png" width="84px" height="35px" data-latex="$$" />.</p>
  144. <p>所以<img src="files/image122.png" width="40px" height="35px" data-latex="$$" />的最大值为<img src="files/image134.png" width="12px" height="19px" data-latex="$$" />.</p>
  145. <p>故答案为:<img src="files/image134.png" width="12px" height="19px" data-latex="$$" />.</p>
  146. <p>【点睛】本题主要考查平面向量的坐标运算、三角函数的性质以及辅助角公式,属于常考题.</p>
  147. <p>三、计算题(本大题6小题,共70分。解答应写出文字说明、证明过程或演算步骤)</p>
  148. <p>17.已知向量<img src="files/image135.png" width="72px" height="28px" data-latex="$$" />,<img src="files/image136.png" width="71px" height="32px" data-latex="$$" />,求<img src="files/image137.png" width="29px" height="23px" data-latex="$$" />及向量<img src="files/image34.png" width="13px" height="23px" data-latex="$$" />与<img src="files/image35.png" width="13px" height="23px" data-latex="$$" />的夹角<img src="files/image138.png" width="13px" height="19px" data-latex="$$" />.</p>
  149. <p>【答案】<img src="files/image139.png" width="61px" height="23px" data-latex="$$" />;<img src="files/image140.png" width="51px" height="41px" data-latex="$$" /></p>
  150. <p>【解析】</p>
  151. <p>【分析】</p>
  152. <p>根据平面向量数量积坐标计算公式直接计算即可.</p>
  153. <p>【详解】解:<img src="files/image124.png" width="15px" height="13px" data-latex="$$" />向量<img src="files/image135.png" width="72px" height="28px" data-latex="$$" />,<img src="files/image136.png" width="71px" height="32px" data-latex="$$" />,</p>
  154. <p> <img src="files/image131.png" width="15px" height="13px" data-latex="$$" /><img src="files/image141.png" width="165px" height="24px" data-latex="$$" />,<img src="files/image142.png" width="43px" height="32px" data-latex="$$" />,<img src="files/image33.png" width="41px" height="32px" data-latex="$$" />,</p>
  155. <p><img src="files/image131.png" width="15px" height="13px" data-latex="$$" /><img src="files/image143.png" width="121px" height="56px" data-latex="$$" />, </p>
  156. <p>又<img src="files/image144.png" width="64px" height="19px" data-latex="$$" />,</p>
  157. <p><img src="files/image131.png" width="15px" height="13px" data-latex="$$" /><img src="files/image140.png" width="51px" height="41px" data-latex="$$" />.</p>
  158. <p>【点睛】本题考查平面向量的坐标运算及夹角公式,熟记公式是解题的关键,属于常考题.</p>
  159. <p>18.(1)求值<img src="files/image145.png" width="368px" height="27px" data-latex="$$" /></p>
  160. <p>(2)化简<img src="files/image146.png" width="284px" height="69px" data-latex="$$" /></p>
  161. <p>【答案】(1)<img src="files/image147.png" width="16px" height="42px" data-latex="$$" />;(2)<img src="files/image148.png" width="100px" height="27px" data-latex="$$" />.</p>
  162. <p>【解析】</p>
  163. <p>【分析】</p>
  164. <p>(1)先利用诱导公式化简成特殊角的三角函数,然后根据特殊角的三角函数值进行计算;</p>
  165. <p>(2)直接用诱导公式化简即可.</p>
  166. <p>【详解】(1)<img src="files/image145.png" width="368px" height="27px" data-latex="$$" /></p>
  167. <p><img src="files/image149.png" width="247px" height="24px" data-latex="$$" /> </p>
  168. <p><img src="files/image150.png" width="135px" height="45px" data-latex="$$" /> </p>
  169. <p><img src="files/image151.png" width="29px" height="38px" data-latex="$$" />;</p>
  170. <p>(2)<img src="files/image146.png" width="284px" height="69px" data-latex="$$" /></p>
  171. <p><img src="files/image152.png" width="208px" height="67px" data-latex="$$" /> </p>
  172. <p><img src="files/image153.png" width="160px" height="44px" data-latex="$$" /></p>
  173. <p><img src="files/image154.png" width="63px" height="15px" data-latex="$$" /></p>
  174. <p>【点睛】本题考查三角函数式的化简,熟练运用诱导公式进行计算是关键,诱导公式口诀“奇变偶不变,符号看象限”,属于常考题.</p>
  175. <p>19.平面内给定三个向量<img src="files/image155.png" width="63px" height="28px" data-latex="$$" />,<img src="files/image156.png" width="70px" height="30px" data-latex="$$" />,<img src="files/image157.png" width="60px" height="28px" data-latex="$$" /></p>
  176. <p>(1)求<img src="files/image158.png" width="85px" height="32px" data-latex="$$" />;</p>
  177. <p>(2)若<img src="files/image159.png" width="120px" height="32px" data-latex="$$" />,求实数<img src="files/image46.png" width="13px" height="19px" data-latex="$$" />的值.</p>
  178. <p>【答案】(1)<img src="files/image160.png" width="32px" height="24px" data-latex="$$" />;(2)<img src="files/image161.png" width="36px" height="19px" data-latex="$$" />.</p>
  179. <p>【解析】</p>
  180. <p>【分析】</p>
  181. <p>(1)先根据平面向量的坐标计算<img src="files/image162.png" width="80px" height="23px" data-latex="$$" />,再根据平面向量的模长计算公式进行计算;</p>
  182. <p>(2)根据向量平行的条件即可得出.</p>
  183. <p>【详解】解:(1)∵<img src="files/image163.png" width="291px" height="28px" data-latex="$$" /></p>
  184. <p>∴<img src="files/image164.png" width="129px" height="32px" data-latex="$$" />;</p>
  185. <p>(2)∵<img src="files/image165.png" width="253px" height="28px" data-latex="$$" />,<img src="files/image166.png" width="93px" height="28px" data-latex="$$" />,</p>
  186. <p>且<img src="files/image159.png" width="120px" height="32px" data-latex="$$" /> </p>
  187. <p>∴<img src="files/image167.png" width="209px" height="27px" data-latex="$$" />.</p>
  188. <p>【点睛】本题考查平面向量平行的坐标表示以及模长计算,熟记公式是解题的关键,属于基础题.</p>
  189. <p>20.已知<img src="files/image32.png" width="40px" height="32px" data-latex="$$" />,<img src="files/image168.png" width="53px" height="32px" data-latex="$$" />.</p>
  190. <p>(1)若<img src="files/image34.png" width="13px" height="23px" data-latex="$$" />与<img src="files/image35.png" width="13px" height="23px" data-latex="$$" />的夹角为<img src="files/image36.png" width="27px" height="19px" data-latex="$$" />,求<img src="files/image169.png" width="40px" height="32px" data-latex="$$" />;</p>
  191. <p>(2)若<img src="files/image170.png" width="32px" height="21px" data-latex="$$" />与<img src="files/image34.png" width="13px" height="23px" data-latex="$$" />垂直,求<img src="files/image34.png" width="13px" height="23px" data-latex="$$" />与<img src="files/image35.png" width="13px" height="23px" data-latex="$$" />的夹角.</p>
  192. <p>【答案】(1)<img src="files/image171.png" width="59px" height="28px" data-latex="$$" />;(2)<img src="files/image172.png" width="27px" height="19px" data-latex="$$" />.</p>
  193. <p>【解析】</p>
  194. <p>【分析】</p>
  195. <p>(1)先计算出<img src="files/image173.png" width="68px" height="45px" data-latex="$$" />,再根据<img src="files/image174.png" width="237px" height="40px" data-latex="$$" />代值进行计算;</p>
  196. <p>(2)设<img src="files/image34.png" width="13px" height="23px" data-latex="$$" />与<img src="files/image35.png" width="13px" height="23px" data-latex="$$" />的夹角为<img src="files/image138.png" width="13px" height="19px" data-latex="$$" />,若<img src="files/image170.png" width="32px" height="21px" data-latex="$$" />与<img src="files/image34.png" width="13px" height="23px" data-latex="$$" />垂直,则有<img src="files/image175.png" width="88px" height="32px" data-latex="$$" />,由此求得<img src="files/image176.png" width="37px" height="19px" data-latex="$$" />的值,然后得出<img src="files/image138.png" width="13px" height="19px" data-latex="$$" />的值.</p>
  197. <p>【详解】解:(1)∵<img src="files/image32.png" width="40px" height="32px" data-latex="$$" />,<img src="files/image168.png" width="53px" height="32px" data-latex="$$" />,<img src="files/image34.png" width="13px" height="23px" data-latex="$$" />与<img src="files/image35.png" width="13px" height="23px" data-latex="$$" />的夹角为<img src="files/image36.png" width="27px" height="19px" data-latex="$$" />,</p>
  198. <p>∴<img src="files/image177.png" width="271px" height="45px" data-latex="$$" />,</p>
  199. <p>∴<img src="files/image178.png" width="437px" height="49px" data-latex="$$" />;</p>
  200. <p>(2)设<img src="files/image34.png" width="13px" height="23px" data-latex="$$" />与<img src="files/image35.png" width="13px" height="23px" data-latex="$$" />的夹角为<img src="files/image138.png" width="13px" height="19px" data-latex="$$" />,</p>
  201. <p>∵<img src="files/image179.png" width="73px" height="32px" data-latex="$$" />,</p>
  202. <p>∴<img src="files/image175.png" width="88px" height="32px" data-latex="$$" />即<img src="files/image180.png" width="83px" height="25px" data-latex="$$" />,</p>
  203. <p>∴<img src="files/image181.png" width="137px" height="23px" data-latex="$$" /> ,</p>
  204. <p>∴<img src="files/image182.png" width="76px" height="45px" data-latex="$$" />,</p>
  205. <p>又∵<img src="files/image183.png" width="75px" height="16px" data-latex="$$" />,</p>
  206. <p>∴<img src="files/image184.png" width="52px" height="19px" data-latex="$$" />,</p>
  207. <p>即<img src="files/image34.png" width="13px" height="23px" data-latex="$$" />与<img src="files/image35.png" width="13px" height="23px" data-latex="$$" />的夹角为<img src="files/image172.png" width="27px" height="19px" data-latex="$$" />.</p>
  208. <p>【点睛】本题考查向量的模的计算、向量垂直的条件以及向量夹角的计算,应正确理解并熟练运用公式进行计算,属于常考题.</p>
  209. <p>21.已知A、B、C是△ABC的三个内角,向量m=(-1,<img src="files/image185.png" width="24px" height="24px" data-latex="$$" />),n=(cosA,sinA),且m·n=1.</p>
  210. <p>(1)求角A;</p>
  211. <p>(2)若<img src="files/image186.png" width="101px" height="41px" data-latex="$$" />=-3,求tanC.</p>
  212. <p>【答案】(1) <img src="files/image187.png" width="16px" height="37px" data-latex="$$" />;(2) <img src="files/image188.png" width="56px" height="46px" data-latex="$$" />.</p>
  213. <p>【解析】</p>
  214. <p>试题分析:(1)由m·n=1,代入坐标用两角和与差的正弦公式化简,即可求出角A;(2)将已知条件用完全平方公式和平方差公式化简,可得<img src="files/image189.png" width="81px" height="41px" data-latex="$$" />=-3,分式上下同除以<img src="files/image190.png" width="39px" height="19px" data-latex="$$" />,解出<img src="files/image191.png" width="39px" height="19px" data-latex="$$" />,又tanC=tan[π-(A+B)],利用诱导公式和两角和与差的正切公式化简,把<img src="files/image192.png" width="39px" height="19px" data-latex="$$" />和<img src="files/image191.png" width="39px" height="19px" data-latex="$$" />的值代入即可.</p>
  215. <p>试题解析:</p>
  216. <p> (1)∵m·n=1,</p>
  217. <p>∴<img src="files/image193.png" width="24px" height="24px" data-latex="$$" />sinA-cosA=1,2(sinA·<img src="files/image194.png" width="27px" height="45px" data-latex="$$" />-cosA·<img src="files/image195.png" width="16px" height="41px" data-latex="$$" />)=1,</p>
  218. <p>sin(A-<img src="files/image196.png" width="17px" height="41px" data-latex="$$" />)=<img src="files/image195.png" width="16px" height="41px" data-latex="$$" />,</p>
  219. <p>∵0&lt;A&lt;π,-<img src="files/image196.png" width="17px" height="41px" data-latex="$$" />&lt;A-<img src="files/image196.png" width="17px" height="41px" data-latex="$$" />&lt;<img src="files/image197.png" width="25px" height="41px" data-latex="$$" />,</p>
  220. <p>∴A-<img src="files/image196.png" width="17px" height="41px" data-latex="$$" />=<img src="files/image196.png" width="17px" height="41px" data-latex="$$" />.∴A=<img src="files/image198.png" width="17px" height="41px" data-latex="$$" />.</p>
  221. <p>(2)由题知<img src="files/image199.png" width="95px" height="41px" data-latex="$$" />=-3,</p>
  222. <p>∴<img src="files/image200.png" width="181px" height="53px" data-latex="$$" />=-3</p>
  223. <p>∴<img src="files/image189.png" width="81px" height="41px" data-latex="$$" />=-3</p>
  224. <p>∴<img src="files/image201.png" width="57px" height="41px" data-latex="$$" />=-3,∴tanB=2.</p>
  225. <p>∴tanC=tan[π-(A+B)]</p>
  226. <p>=-tan(A+B)=-<img src="files/image202.png" width="85px" height="41px" data-latex="$$" />=<img src="files/image203.png" width="56px" height="45px" data-latex="$$" />.</p>
  227. <p>点睛:本题考查平面向量数量积的坐标运算,同角三角函数的基本关系和两角和与差的正切公式. 平面向量的数量积计算问题,往往有两种形式,一是利用数量积的定义式,二是利用数量积的坐标运算公式,涉及几何图形的问题,先建立适当的平面直角坐标系,可起到化繁为简的妙用. 利用向量夹角公式、模公式及向量垂直的充要条件,可将有关角度问题、线段长问题及垂直问题转化为向量的数量积来解决.列出方程组求解未知数.</p>
  228. <p>22.已知函数<img src="files/image204.png" width="333px" height="45px" data-latex="$$" />的最大值为<img src="files/image134.png" width="12px" height="19px" data-latex="$$" />,<img src="files/image205.png" width="39px" height="27px" data-latex="$$" /></p>
  229. <p>的图像的相邻两对称轴间的距离为<img src="files/image29.png" width="13px" height="17px" data-latex="$$" />,与<img src="files/image206.png" width="14px" height="18px" data-latex="$$" />轴的交点坐标为<img src="files/image207.png" width="37px" height="21px" data-latex="$$" />.</p>
  230. <p>(1)求函数<img src="files/image205.png" width="39px" height="27px" data-latex="$$" />的解析式;</p>
  231. <p>(2)设数列<img src="files/image208.png" width="69px" height="27px" data-latex="$$" />,<img src="files/image209.png" width="19px" height="24px" data-latex="$$" />为其前<img src="files/image210.png" width="13px" height="15px" data-latex="$$" />项和,求<img src="files/image211.png" width="27px" height="24px" data-latex="$$" />.</p>
  232. <p>【答案】(1)<img src="files/image212.png" width="137px" height="45px" data-latex="$$" />(2)<img src="files/image213.png" width="68px" height="24px" data-latex="$$" />.</p>
  233. <p>【解析】</p>
  234. <p>【分析】</p>
  235. <p>(1)根据题中条件,先求出<img src="files/image214.png" width="36px" height="16px" data-latex="$$" />,再由对称轴距离得到<img src="files/image215.png" width="41px" height="41px" data-latex="$$" />,求出<img src="files/image216.png" width="45px" height="41px" data-latex="$$" />,进而可求出结果;</p>
  236. <p>(2)先由(1)得到<img src="files/image217.png" width="167px" height="45px" data-latex="$$" />,分别讨论<img src="files/image210.png" width="13px" height="15px" data-latex="$$" />为偶数与<img src="files/image210.png" width="13px" height="15px" data-latex="$$" />为奇数,即可求出结果.</p>
  237. <p>【详解】(1)∵<img src="files/image218.png" width="212px" height="41px" data-latex="$$" />,依题意:<img src="files/image219.png" width="88px" height="41px" data-latex="$$" />,∴<img src="files/image214.png" width="36px" height="16px" data-latex="$$" />.</p>
  238. <p>又<img src="files/image215.png" width="41px" height="41px" data-latex="$$" />,∴<img src="files/image220.png" width="51px" height="41px" data-latex="$$" />,得<img src="files/image216.png" width="45px" height="41px" data-latex="$$" />.∴<img src="files/image221.png" width="172px" height="45px" data-latex="$$" />. 令<img src="files/image222.png" width="37px" height="19px" data-latex="$$" />得:<img src="files/image223.png" width="91px" height="21px" data-latex="$$" />,又<img src="files/image224.png" width="67px" height="41px" data-latex="$$" />,∴<img src="files/image225.png" width="53px" height="41px" data-latex="$$" />.</p>
  239. <p>故函数<img src="files/image205.png" width="39px" height="27px" data-latex="$$" />的解析式为:<img src="files/image212.png" width="137px" height="45px" data-latex="$$" /></p>
  240. <p>(2)由<img src="files/image212.png" width="137px" height="45px" data-latex="$$" />知:<img src="files/image217.png" width="167px" height="45px" data-latex="$$" />.</p>
  241. <p>当<img src="files/image210.png" width="13px" height="15px" data-latex="$$" />为偶数时,<img src="files/image226.png" width="63px" height="27px" data-latex="$$" />;</p>
  242. <p>当<img src="files/image210.png" width="13px" height="15px" data-latex="$$" />为奇数时,<img src="files/image227.png" width="344px" height="27px" data-latex="$$" />.</p>
  243. <p>∴<img src="files/image228.png" width="171px" height="24px" data-latex="$$" />.</p>
  244. <p>【点睛】本题主要考查三角函数的性质,熟记相关知识点即可,属于常考题型.</p>
  245. <p> </p>
  246. <p> </p>
  247. <p> </p>
  248. <p> </p>
  249. </body></html>