Answer
$\sin (- 120)^{\circ}$ = - 0.8660
Work Step by Step
Using calculator in degree mode-
(- 120) → $\sin$
$\sin (- 120)^{\circ}$ = - 0.8660254038
Rounding it to four places past the decimal point-
$\sin (- 120)^{\circ}$ = - 0.8660