$\displaystyle \int _ {0} ^ {\sqrt 3} {\sin \left (\tan ^ {-1} x \right)} dx$ 의 값은?

• ①$\displaystyle \frac{1} {2}$
• ②$\displaystyle \frac{3} {4}$
• ③$1$
• ④$\displaystyle \frac{3} {2}$