8 tan square theta - 8 sec square theta

Answer 1

since sec^2 θ - tan^2 θ = 1, you have

-8(sec^2 θ - tan^2 θ) = -8

Better review your basic identities. The most important is, of course,

sin^2 θ + cos^2 θ = 1

divide through by cos^2 and you have

tan^2 θ + 1 = sec^2 θ