2 cos 2x= sin 2x cot x-2 sin^2x
cos2x = cos^2x - sin^2x
2(cos^2x -sin^2x)= sin 2x cot x-2 sin^2x
2 cos ^2x-2sin^2x= sin 2x cot x-2 sin^2x
2 cosxcosx-2sin^2x= sin 2x cot x-2 sin^2x
2cosxcosxsinx/sinx-2sin^2x= sin 2x cot x-2 sin^2x
2sinxcosx = sin2x
sin2xcosx/sinx-2sin^2x= sin 2x cot x-2 sin^2x
sin2xcotx-2sin^2x= sin 2x cot x-2 sin^2x