Question

-tan^2x+sec^2x=1 proving identity help?

Answer 1

\[-\tan^2x +\sec^2x = 1
\\\sec^2x = 1+\tan^2x
\\\frac{1}{\cos^2x} = \frac{\cos^2x}{\cos^2x} + \frac{\sin^2x}{\cos^2x}
\\1 = \cos^2x + \sin^2x
\\1 = 1

\]