[Math] $\tan^2x – \sec^2x$ express in terms of sin/cos

Question

I am trying to express this problem in terms of sin/cos and simplify. I couldn't figure out where to go, I tried as best I could. I know the answer is -1 but I am more interested to know how to do this problem.

$$
\tan^2x – \sec^2x
$$

$$
(\sin x / \cos x)^2 – (x / \cos x)^2
$$

Answer 1

$$\tan^2x-\sec^2x=\frac{\sin^2x-1}{\cos^2x}=\frac{-\cos^2x}{\cos^2x}=-1.$$