$1)$What is the value of $\sin 15^{o}$
$\sin 15^{o}=\sin \left ( 60^{o}-45^{o} \right )$
$=\sin 60^{o}.\cos 45^{o}-\cos 60^{o}.\sin 45^{o}$
$=\left ( \frac{\sqrt{3}}{2} \right ).\left ( \frac{1}{\sqrt{2}} \right )-\left ( \frac{1}{2} \right ).\left ( \frac{1}{\sqrt{2}} \right )$
$=\frac{\sqrt{3}-1}{2\sqrt{2}}$
$=\frac{\sqrt{3}-1}{2\sqrt{2}}=0.258$
Is it correct?
$2)$ $\sin 80^{o}$ value=_____________
Is it possible to do?