$\displaystyle \arcsin \frac{\sqrt {3}} {2} + \arctan \left (\tan \frac{5 \pi} {9} \right)$ 의 값은?

• ①$\displaystyle - \frac{5 \pi} {18}$
• ②$\displaystyle - \frac{\pi} {9}$
• ③$\displaystyle \frac{4 \pi} {9}$
• ④$\displaystyle \frac{13 \pi} {18}$
• ⑤$\displaystyle \frac{8 \pi} {9}$