Question

using the Pythagorean identity, we have tan^2 theta... fill in the rest

Answer 1

tan^2 theta = sec^2 theta - 1 although there are other identities involving tan^2 theta

Answer 2

what are the others?

Answer 3

Many. From the link below, I see( 1 + tan^2 theta = sec^2 theta) listed as a Pythagorean identity. I solved for tan^2 theta because I thought that was the question. However, it may be to list the identity in its original form.

http://www.sosmath.com/trig/Trig5/trig5/trig5.html