SOLUTION: thank you mr/mrs for helping me in advance. this website probably fell from heaven. i have some problems understanding from my math teacher and i dont want to get lost in the subj

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Question 995712: thank you mr/mrs for helping me in advance.
this website probably fell from heaven. i have some problems understanding from my math teacher and i dont want to get lost in the subject
the question is :
prove the following identities
1-tan^2x/1+tan^2x=cos^2-sin^2x
thank you

Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
prove the following identities
1-tan^2x/1+tan^2x = cos^2(x)-sin^2x
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Note:: 1+tan^2(x) = sec^2(x)
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Substitute to get:
(1-tan^2)/sec^2 = cos^2 - sin^2
----
Multiply thru by sec^2 to get:
1-tan^2 = 1-tan^2
-------------
Cheers,
Stan H.
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