Find the principal solutions of the equation $\sin x = \frac{\sqrt{3}}{2}$.

• A
  $\frac{\pi}{3}$ and $\frac{2\pi}{3}$
• B
  $\frac{\pi}{6}$ and $\frac{5\pi}{6}$
• C
  $\frac{\pi}{4}$ and $\frac{3\pi}{4}$
• D
  $\frac{2\pi}{3}$ and $\frac{4\pi}{3}$