$\displaystyle \lim _ {\theta \rightarrow 0} \left (\frac{{\cot} 2 \theta} {{\csc} \theta} - \frac{{\sin} ({\cos} \theta)} {{\sec} \theta} \right)$ 의 값은?

• ①$- {\sin} 1$
• ②${\sin} 1$
• ③$\displaystyle \frac{1} {2} - {\sin} 1$
• ④$\displaystyle \frac{1} {2} + {\sin} 1$