Accedmychevron_right11thchevron_rightmathchevron_rightComplex Numberschevron_rightExercise 1.5

(iv) (5,5π6)(5,\dfrac{5\pi}{6})

Here r=5>0r=5>0 and θ=5π6\theta=\dfrac{5\pi}{6}.

x=5cos5π6=532y=5sin5π6=52\begin{aligned} x&=5\cos\frac{5\pi}{6}=-\frac{5\sqrt{3}}{2}\\ y&=5\sin\frac{5\pi}{6}=\frac{5}{2} \end{aligned}