Question

Which of the following is not an identity?

A. 1+cos^2x/ Sin^2x = 1

B. (cosx+Sinx)^2= 1+2cosx sinx

C. tan^2x=sec^2x-sin^2-cos^2x

D. (tanx+cotx)^2=csc^2x+sec^2x

Answer 1

cos^2x + sin^2x = 1
sin^2x = 1 - cos^2 x
so A is not an identity

Answer 2

Thank you very much Cwrw238

Answer 3

your welcome