MCQ
Polar form of $z=4+4 \sqrt{3} i$ is
  • $8\left(\cos \frac{\pi}{3}+i \sin \frac{\pi}{3}\right)$
  • B
    $4\left(\cos \frac{2 \pi}{3}+i \sin \frac{2 \pi}{3}\right)$
  • C
    $8\left(\cos \frac{5 \pi}{3}+i \sin \frac{5 \pi}{3}\right)$
  • D
    $4\left(\cos \frac{\pi}{3}+i \sin \frac{\pi}{3}\right)$

Answer

Correct option: A.
$8\left(\cos \frac{\pi}{3}+i \sin \frac{\pi}{3}\right)$
(A)
$z =4+4 \sqrt{3} i$
$|z|=\sqrt{4^2+(4 \sqrt{3})^2}=8$
Also, $a=4$ and $b=4 \sqrt{3}$
$\therefore \quad \theta=\tan ^{-1}\left(\frac{4 \sqrt{3}}{4}\right)=\tan ^{-1}(\sqrt{3})=\frac{\pi}{3}$
Polar form of $z=|z|(\cos \theta+i \sin \theta)$
$=8\left(\cos \frac{\pi}{3}+ i \sin \frac{\pi}{3}\right)$

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