题目
sin105°cos105°的值为______.
提问时间:2020-12-14
答案
sin105°cos105°
=sin(60°+45°)cos(60°+45°)
=(sin60°cos45°+cos60°sin45°)(cos60°cos45°-sin60°sin45°)
=(
=sin(60°+45°)cos(60°+45°)
=(sin60°cos45°+cos60°sin45°)(cos60°cos45°-sin60°sin45°)
=(
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