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**number0001**- Replies: 3

I got another trig problem, which is to prove (make the left side of the "=" equal to the right side).

(cos3x-cosx)/(sin3x-sinx)=-tan2x

I tried it but got stuck. Thanks very much for any help!

Thank you so much! That was very helpful--now I get it!

**number0001**- Replies: 2

How do you do cos(3x)=4cos^3(X)-3cos(X)? I mean, I got to somehow transform the left side of the = sign so it looks exactly like the right side. Kind of like a proof. I think I need some of the trig formulas for this but I can't really get it... Thanks for any help!

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