Ubahlah (2, 120°) ke kordinat cartesius

X = r cos a
y = r sin a
.
(r, a) =(2, 120°)
x = 2 cos 120 = 2 (-1/2) = -1
y = 2 sin 120 = 2 (1/2 √3) = √3

(x,y) =  ( – 1,  √3)