Which of the following is an identity?

A. csc^2 x + cot^2 x = 1

B. (cscx + cotx) ^2 = 1

C. sec^2 x sec^2 x + 1 = tan^2 x csc^2 x

D. sin^2 x - cos^2 x = 1

I am not sure at all but I think the answer is C.

There is an identity csc^2 x = 1 + cot^2x so it cant be A

Nor D because sin^2 x + cos^2 x = 1

I think Its C

converting to sin's and cos's

1 / cos^4 x + 1 = sin^2 x / cos^2x * 1 / sin^2 x = 1 / cos^2 x

I dont think any are identities

You sure you have the question correct?