Question

sin^2 theta-cos^2 theta=0

Answer 1

\[\large{\sin^2{\theta} - \cos^2 {\theta} = 0}\]

I can write this as :

\[\large{\cos^2 {\theta} - \sin^2{\theta} = 0}\]

Answer 2

Then, I use this formula:

\[\large{\cos (2x) = \cos^2 x - \sin^2 x}\]

Thus, I get,

\[\large{\cos(2\theta) = 0}\]