计算cos(35°+x)cos(25°-x)-cos(55°-x)sin(25°-x)=_.
题目
计算cos(35°+x)cos(25°-x)-cos(55°-x)sin(25°-x)=______.
答案
cos(35°+x)cos(25°-x)-cos(55°-x)sin(25°-x)
=cos(35°+x)cos(25°-x)-sin(35°+x)sin(25°-x)
=cos(35°+x+25°-x)
=cos60°
=
.
故答案为:
.
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