Question

Find all angles x [0, 2π), such that cos(2x) = 2sin(x) = -3 ?

Answer 1

See explanation.

Explanation:

If there is no mistake in the question then the answer is: There are NO real numbers `x` satisfying this equation.

Both `sinx` and `cosx` are limited functions. Their range is `<-1;1>`, so `cosx` or `cos2x` CANNOT be equal to `-3`.