Question

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

Answer 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