Miranda P.

asked • 12/26/18

cos3x = 1- 3cosx Solve for x

what I did:

cos(2x + x) = 1-3cosx

used compound angle formula

cos2xcosx - sin2xsinx = 1- 3cosx

used double angle formulae for both cos2x and sin2x

(1-2sin^2x)cosx - 2sin^2xcosx = 1-3cosx

but I'm stuck now.

Any help appreciated.

1 Expert Answer


Miranda P.

Thanks a lot


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