tan2x-cot2xtan2x−cot2x
=(sin2x)/(cos2x)-(cos2x)/(sin2x)=sin2xcos2x−cos2xsin2x
=(sin^2 2x-cos^2 2x)/(sin2xcos2x)=sin22x−cos22xsin2xcos2x
=-(2(cos^2 2x-sin^2 2x))/(2*sin2xcos2x)=−2(cos22x−sin22x)2⋅sin2xcos2x
=-(2cos4x)/(sin4x)=−2cos4xsin4x
=-cot4x=−cot4x