Plis bantuin jawab pakai cara ya

[tex] \cos(120) = \cos(2.60) = {( \cos(60) })^{2} - {( \sin(60) })^{2} \\ = \frac{1}{4} - \frac{3}{4} = - \frac{1}{2} \\ \sin(150) = \sin(90 + 60) = \sin(90) \cos(60) + \cos(90) \sin(60) \\ = \frac{1}{2} \\ \sin(30) = \frac{1}{2} \\ \frac{4( - \frac{1}{2} - \frac{1}{2} )}{ \frac{1}{2} } = - 8[/tex]