已知0<β<π/4<α<3π/4,cos(π/4-α)=3/5,sina(3π/4+β)=5/13,求sina(α+β)的值

问题描述:

已知0<β<π/4<α<3π/4,cos(π/4-α)=3/5,sina(3π/4+β)=5/13,求sina(α+β)的值

0<β<π/4<α<3π/4
可知-
-π/2