Question

cos(Pi/2-3х)+sin(Pi-x)=2cosx

Answer 1

sin2x+sinx=2cosx+1

sinx(2cosx+1) - (2cosx+1) = 0

(2cosx+1)(sinx-1) = 0

Разбиваем на 2 уравнения:

2cosx+1 = 0                            sinx-1 = 0

cosx=-1/2                               sinx = 1