Question

Which of the following is not an identity?

A. (tanx + cotx)^2 = csc^2 x + sec^2 x
B. (cosx + sinx)^2 = 1 + 2cosx sinx
C. tan^2x = sec^2x - sin^2x - cos^2x
D. 1+cos^2x/sin^2x=1

Answer 1

You will have to verify each to see which is not an identity

Answer 2

how do i do that

Answer 3

verification involves you changing one side and trying to make it appear like the second side by manipulating the trig expressions