SOLUTION: I need help, I don't understand how to do this.. Find all solutions to the equation. 7 sin2x - 14 sin x + 2 = -5

Algebra ->  Trigonometry-basics -> SOLUTION: I need help, I don't understand how to do this.. Find all solutions to the equation. 7 sin2x - 14 sin x + 2 = -5      Log On


   

Question 1005892: I need help, I don't understand how to do this..
Find all solutions to the equation.
7 sin2x - 14 sin x + 2 = -5
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
It's a quadratic equation in disguise.
Let u=sin%28x%29, then,
7u%5E2-14u%2B7=0
u%5E2-2u%2B1=0
Now solve the quadratic in u and back substitute to get the solution in x.
Repost if you get stuck.