Tentukan nilai dari : a.cos 120° b.sin 240°

TRIGONOMETRI

a.
cos120° = cos(90°+30°) = - sin30° = -1/2

b.
sin240° = sin(180°+60°) = -sin60° = -1/2 akar3

a. cos 120˚
= cos (180-60)˚
= -cos 60˚
= -1/2

b. sin 240˚
= sin (180+60)˚
= -sin 60˚
= -1/2 √3