Question

решите уравнение

sin ( 5пи - х ) = cos (2x + 7 пи)

Answer 1

sin (pi -x) = cos (pi +2x)

sin x = -cos 2x

sin x +1-2sin ^2 (x) = 0

2a^2 +a +1 = 0

a = 1/2    a = -1

sin x = 1/2

x = (-1)^n * (pi/6) +pin

 

sin x = -1

x  = -pi/2 +2pin