Question:
Find the value of the trigonometric function $\sin 765^{\circ}$
Solution:
It is known that the values of $\sin x$ repeat after an interval of $2 \pi$ or $360^{\circ}$
$\therefore \sin 765^{\circ}=\sin \left(2 \times 360^{\circ}+45^{\circ}\right)=\sin 45^{\circ}=\frac{1}{\sqrt{2}}$