Question

Find all solutions to the equation.

7 sin2x - 14 sin x + 2 = -5

Answer 1

I suppose the question is \[7 sin ^{2}x - 14 sin x +2 = -5\]

Answer 2

If so, then substitute X in place of sin x. You get,
\[7X ^{2}-14X+2=-5\]

Answer 3

This is a quadratic equaiton which can be solved for the values of X.
Then use trigonometric tables to find the angle at which sine has this value.