2 sin x × Cos x – cos x / 1-sin x +sin2x – cos2x = cot x

2 sin x . Cos x – cos x / 1-sin x +sin² x – cos² x = cot x
inget cos² x = 1 – sin²x

jadi 
2  sin x . Cos x – cos x/ 1-sin x +sin² x - (1 – sin²x)= cot x
2  sin x . Cos x – cos x/ 2 sin² x - sin x = cot x
cos x (2 sin x – 1)/ sin x (2 sin x – 1  ) = cot x
cos x/sin x = cot x
        cot x = cot x