Question

Which of the following are identities? Check all that apply.

A. cot^2 x + 1 = csc^2 x
B. tan^2 x = 1 - sec^2 x
C. sin^2 x = 1 + cos^2 x
D. sin^2 x + cos^2 x = 1

Answer 1

The fourth one is

Answer 2

And the first one is also one