which of the following are NOT trigonometric identities, Check all that apply a.) sec^ (2) x - tan^ (2) x=1 b) sec^ (2) x+csc^ (2) x=1 c) sin^ (2) x + cos^ (2) x=1 d) tan^ (2) x + sec^ (2) x = 1

By looking the given options, we can say that some of them are following pythagorean identities and pythagorean identities are

sin^2 (x) + cos^2 (x) = 1, sec^2 (x) - tan^2 (x) = 1, csc^2 (x) - cot^2 (x) = 1

So out the four options, option a and option c are following pythagorean identity and option b and option d are not following pythagorean identity. And we have to find those options which are not identities.

So the correct options are

b) sec^{2} x+csc^{2} x=1 / d) tan^{2} x + sec^{2} x = 1