## anonymous one year ago can a anyone explain how to do this problems? Find all solutions to the equation. 7 sin2x - 14 sin x + 2 = -5

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1. Nnesha

set it equal to 0

2. Nnesha

let sinx= x write it as quadratic equation $\huge\rm 7x^2 -14x +2 +5 =0$

3. anonymous

7sin2x - 14sinx + 2 = -5 7sin2x - 14sinx = -7 7(sin2x - 2sinx) = -7 sin2x - 2sinx = -1 2sinxcosx - 2sinx = -1 2sinx (cosx - 1) = -1 Now solve 2sinx = -1 cosx - 1 ==1

4. alekos

Are we looking at $\sin ^{2}x$ or sin2x