If 3A = 1 and 0 < A < 90^ , find 2A - Vidyadip

Question

If $\sin 3A = 1$ and $0 < A < 90^\circ,$ find $ \cos 2A$

✓

Answer

$\sin 3A = 1$
$\sin 3A = \sin90^\circ$
$3A = 90^\circ$
$A = 30^\circ$
$\cos 2A = \cos 2(30^\circ)$
$= \cos 60^\circ$
$=\frac{1}{2}$

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