tan^2x/sin^2x=1+tan^2x
I assume you want to prove that they are equal
tan/sin = sec
so,
sec^2 = 1+tan^2
that is one of your fundamental identities, obtained by dividing by cos^2 in
sin^2 + cos^2 = 1
tan/sin = sec
so,
sec^2 = 1+tan^2
that is one of your fundamental identities, obtained by dividing by cos^2 in
sin^2 + cos^2 = 1