1$\cos^2 x + \sin^2 x$ = ?
1
2$1 + \tan^2 x$ = ?
$\sec^2 x$
3$\sin 2x$ = ?
$2 \sin x \cos x$
4$\cos 2x$ = ?
$\cos^2 x - \sin^2 x = 2 \cos^2 x - 1$
5$\tan 2x$ = ?
$\frac{2 \tan x}{1 - \tan^2 x}$
6$\sin^2 x$ = ?
$\frac{1 - \cos 2x}{2}$
7$\cos^2 x$ = ?
$\frac{1 + \cos 2x}{2}$
8$\cos(\arcsin x) = \sin(\arccos x)$ = ?
$\sqrt{1 - x^2}$