Which of the following is equal to 1−cos2x1+cos2x\frac{1-\cos 2x}{1+\cos 2x}1+cos2x1−cos2x?
tan2x\tan^2 xtan2x
cot2x\cot^2 xcot2x
sin2x\sin^2 xsin2x
cos2x\cos^2 xcos2x