Use a Sum or Difference Identity to Find the Exact $\sin 15 ^ { \circ }$

Multiple Choice

Use a sum or difference identity to find the exact value.
- $\sin 15 ^ { \circ }$

A) $\frac { - \sqrt { 6 } + \sqrt { 2 } } { 4 }$
B) $\frac { \sqrt { 6 } + \sqrt { 2 } } { 4 }$
C) $\frac { \sqrt { 6 } - \sqrt { 2 } } { 4 }$
D) $\frac { - \sqrt { 6 } - \sqrt { 2 } } { 4 }$