Question

sin(180-x)+cos(90-3x)+sin5x-sin7x=0

Answer 1

sin(180-x)+cos(90-3x)+sin5x-sin7x=sinx+sin3x+sin5x-sin7x=2sinxcos2x-2sinxcos6x=2sinx(cos2x-cos6x)=4sinxsin2xsin4x=0
Отсюда: x=+-$pi n$; x=+-$pi n/2$ x=+-$pi n/4$