问题标题:
计算:(cos75°+sin75°)(cos75°-sin75°)=___.
问题描述:
计算:(cos75°+sin75°)(cos75°-sin75°)=___.
简政回答:
∵(cos75°+sin75°)(cos75°-sin75°)
=cos275°-sin275°
=cos150°
=-32
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