Question 388619
15 sin 2x = 10 cos x. By double-angle formula, sin 2x = 2 sin x cos x, so


30 sin x cos x = 10 cos x. Move 10 cos x to the other side and divide by 10


3 sin x cos x - cos x = 0


cos x (3 sin x - 1) = 0


cos x = 0 or sin x = 1/3


x = 90, 270, or x = arcsin (1/3)