Question 174276
cot^2x-cos^2x = (cot^2x)(cos^2x) 
So I tried: 
[(cos^2x)/(sin^2x)] - cos^2 = [(cos^2x)/(sin^2x)](cos^2x) 

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Multiply both sides by sin^2(x) to get:
cos^2(x) - sin^2(x)*cos^2(x) = cos^4(x)
(cos^2(x)(1 - sin^2(x)) = cos^4(x)
(cos^2(x))(cos^2(x)) = cos^2(x)*cos^2(x)
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Cheers,
Stan H.