Step-by-step explanation:
[tex] \because \: sin \: ( - \theta) = - sin \: \theta \\ \\ \therefore \: sin \: ( - 120 \degree) = - sin \: 120 \degree \\ \\ = - sin \: ( 180\degree- 60 \degree) \\ \\ = - sin \: 60 \degree \\ \\ = - \frac{ \sqrt{3} }{2} \\ \\ \purple{ \boxed{\therefore \: sin \: ( - 120 \degree) =- \frac{ \sqrt{3} }{2} }}[/tex]
