98
If $\sin 3A = 1$, then find the value of $\cos 2A - \tan^2 45^\circ$.
Show SolutionHide Solution↓
Solution: (a) $3A = 90^\circ \Rightarrow A = 30^\circ$
$\cos 2A - \tan^2 45^\circ = \cos 60^\circ - \tan^2 45^\circ$
$= \frac{1}{2} - 1 = \frac{-1}{2}$
$\cos 2A - \tan^2 45^\circ = \cos 60^\circ - \tan^2 45^\circ$
$= \frac{1}{2} - 1 = \frac{-1}{2}$