Question

Пожалуйста помогите.... cos15x = sin5x

Answer 1

cos15x-cos(π/2-5x)=0
-2sin(10x-π/4)sin(5x+π/4)=0
sin(10x-π/4)=0⇒10x-π/4=π/2+πk⇒10x=3π/4+πk⇒x=3π/40+πk/10,k∈z
sin(5x+π/4)=0⇒5x+π/4=π/2+πk⇒5x=π/4+πk⇒x=π/20+πk/5,k∈z