sin(3π/4-a)+cos(5π/4-a)如何化简

问题描述:

sin(3π/4-a)+cos(5π/4-a)如何化简

sin(3π/4-a)+cos(5π/4-a)
=sin[π-(3π/4-a)]-cos[π-(5π/4-a)]
=sin(a+π/4)-cos(a-π/4)
=sina*√2/2+cosa*√2/2-cosa*√2/2-sina*√2/2
=0