Question

4 sin ^ 2 x- 4 sin x + 1 = 0

Answer 1

`4\sin^2x-4\sin x+1=(2\sin x-1)^2=0\implies \sin x=\frac12`

This happens for
`x=\frac\pi6+2n\pi` and
`x=\frac{5\pi}6+2n\pi` where
`n` is any integer.