Evaluate $\int _ { - 1 } ^ { 1 } \left( 2 - \sqrt { 1 - x ^ { 2 } } \right) d x$

Short Answer

Evaluate $\int _ { - 1 } ^ { 1 } \left( 2 - \sqrt { 1 - x ^ { 2 } } \right) d x$ by interpreting the integral in terms of area.