Question 939398
Prove each identity:
c) cos^2θ=(1-sinθ)(1+sinθ)
(1-sinθ)(1+sinθ)=1-sin^2θ=cos^2θ
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d) sin^2θ+2cos^2θ-1=cos^2θ
1-cos^2θ+2cos^2θ-1=cos^2θ
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e) sin^4θ - cos^4θ =sin^2θ -cos^2θ
I don't think this problem is written correctly
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g) 1-cos^2x=sinxcosx/cotx 
sinxcosx/cotx=sinxcosx/(cosx/sinx)=sin^2x=1-cos^2x