Solving for $\theta$: Which Value is a Counterexample?

[eleventhxhour]

Which value for $\theta$ is a counterexample to sin^2$\theta$+cos^2$\theta$=tan^2$\theta$ as an identity?

a) pi/4
b) 5pi/4
c) pi/3
d) It is an identity

So I tried subbing in each value (a, b, c) in as x and then finding the exact value from that but I'm not getting it.

 

[Dethrone]

Well, you know that $\sin^2\left({x}\right)+\cos^2\left({x}\right)=1$, so the statement you're given above is not an identity, since it does not hold true that $\tan^2\left({x}\right)=1$ for all values of $x$. :)
What can you deduce when you put the numbers on the right side, $\tan^2\left({x}\right)$? (Tongueout)