SOLUTION: Prove. Tan^2(x)+cos2(x)=1-cos2(x)tan^2(x)

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Question 952695: Prove.
Tan^2(x)+cos2(x)=1-cos2(x)tan^2(x)
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Prove.
Tan^2(x)+cos2(x)=1-cos2(x)tan^2(x)
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[sin^2/cos^2) + cos^2 - sin^2 = 1-(cos^2-sin^2)(sin^2/cos^2)
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Multiply thru by cos^2 to get::
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sin^2 + cos^4 - cos^2*sin^2 = cos^2 - cos^2*sin^2 + sin^4
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sin^2 + cos^4 = cos^2 + sin^4
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cos^4-sin^4 = cos^2-sin^2
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Divide both sides by cos^2-sin^2 to get::
cos^2 + sin^2 = 1
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1 = 1
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cheers,
Stan H.
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