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October 22, 2014

October 22, 2014

Posted by **Kate** on Monday, July 18, 2011 at 11:30am.

a) 1-cos^2x=tan^2xcos^2x

b) cos^2x + 2sin^2x-1 = sin^2x

I also tried a question on my own:

tan^2x = (1 – cos^2x)/cos^2x

R.S.= sin^2x/cos^2x

I know that the Pythagorean for that is sin^2x + cos^2x

That's all I could do.

- Math -
**MathMate**, Monday, July 18, 2011 at 11:42ama)

Given tan(θ)=sin(θ)/cos(θ)

substitute tan(θ) by sin(θ)/cos(θ) on the RHS and see what you get.

b) hint:

cos(2θ)=cos²(θ)-sin²(θ)

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