SOLUTION: (cos^4(x)-sin^4(x))/cos^2(x) = 1-tan^2(x) I need the proof, PLEASE

Algebra ->  Trigonometry-basics -> SOLUTION: (cos^4(x)-sin^4(x))/cos^2(x) = 1-tan^2(x) I need the proof, PLEASE      Log On


   

Question 711650: (cos^4(x)-sin^4(x))/cos^2(x) = 1-tan^2(x)
I need the proof, PLEASE
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
(cos^4(x)-sin^4(x))/cos^2(x) = 1-tan^2(x)
Multiply by cos^2
(cos^4(x)-sin^4(x)) = cos^2 - sin^2
(cos^2(x)-sin^2(x))*(cos^2 + sin^2) = cos^2 - sin^2
(cos^2(x)-sin^2(x))*1 = cos^2 - sin^2
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The way to do these is to try things.