Question

Find the value of $\sin {330}^{\circ }\cos {120}^{\circ }$

Answer 1

$\sin {330}^{\circ }\cos {120}^{\circ }$

$=\sin ({360}^{\circ }-{30}^{\circ })\cos ({180}^{\circ }-{60}^{\circ })$

$=-\sin {30}^{\circ }\times -\cos {60}^{\circ }$

$=\sin {30}^{\circ }\cos {60}^{\circ }$

$=\frac{1}{2}\times \frac{1}{2}=\frac{1}{4}$