• cos75°cos15°-sin255°sin165°的值是试题及答案-单选题-云返教育

    • 试题详情

      cos75°cos15°-sin255°sin165°的值是         

      试题解答


      A
      cos75°cos15°-sin255°sin165°
      =cos75°cos15°-sin(180°+75°)sin(180°-15°)
      =cos75°cos15°+sin75°sin15°
      =cos(75°-15°)
      =cos60°
      =

      故选A
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