express \cos^4\theta in terms of powers of \tan\theta and \cos\theta. pls help on the above problem, thanks
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I'll write x instead of theta cos^4x=(1-sin^2x)^2=1-2sin^2x+sin^4x But sinx=tanxcosx So cos^4x=1-2tan^2xcos^2x+tan^4xcos^4x
Originally Posted by lawochekel express \cos^4\theta in terms of powers of \tan\theta and \cos\theta. pls help on the above problem, thanks Hence :
Hello, lawochekel! A slightly different approach . . .
Or an even easier approach cos^4(theta) = cos^4(theta) + tan^0(theta) - 1
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