2sin² (π-x) + 5sin (1,5π+x) = 2

2sin²x-5cosx-2=0

2 (1-cos²x) - 5cosx - 2 = 0

2 - 2cos²x - 5cosx - 2 = 0

cos²x=t

-2t² - 5t = 0

t * (-2t - 5) = 0

t1 = 0 или - 2t-5 = 0

-2t = 5

t = - 2,5 (не существует)

cos²x = 0

cosx = 0

x = π/2 + πk, k∈z