已知π/2<b<a <3π/4,cos(a-b)=12/13,sin(a+b)=-3/5,求sin2a.
问题描述:
已知π/2<b<a <3π/4,cos(a-b)=12/13,sin(a+b)=-3/5,求sin2a.
答
b>π/2
-b