You can put this solution on YOUR website! cot^2 theta-cos^2 theta= (cot^2 theta) (cos^2 theta)
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cot^2-cos^2=(cot^2)(cos^2)
starting with left-hand side,
(cos^2/sin^2-cos^2
=(cos^2-sin^2cos^2)/sin^2
=cos^2(1-sin^2)/sin^2
=cos^2*cos^2/sin^2
=cos^4/sin^2
=(cos^2/sin^2)*cos^2
=(cot^2)(cos^2)
identity confirmed: Left-hand side = right-hand side