<s>[INST] Verifying the identity $\frac{1}{\cos x} - \cos x = \sin x \tan x$ $\frac{1}{\cos x} - \cos x = \sin x  * \tan x$
I have tried a few things and nothing works

Left Side
$\frac{1}{\cos x} - \cos x$
$1 - (\cos x)^2$
$1 - 1 + \frac{\cos 2x}{2}$
$ \frac{\cos 2x}{2}$
$ \frac{\cos x}{2} \times \frac{\cos}{2}$
... And I am out in left field!
 [/INST] $$\frac{1}{\cos x} - \cos x = \frac{1- \cos^2 x}{\cos x}$$
Now I think you can finish.
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