化简:cos(60°-a)-cos(60°+a)=
问题描述:
化简:cos(60°-a)-cos(60°+a)=
答
化简:cos(60°-a)-cos(60°+a)
=cos60°cosa+sin60°sina-(cos60°cosa-sin60°sina)
=cos60°cosa+sin60°sina-cos60°cosa+sin60°sina
=2sin60°sina
=2×√3/2sina
=√3sina