Sketch a Plane Region Whose Area Is Equal To Then Fine the Limit

Essay

Sketch a plane region whose area is equal to $\lim _ { n \rightarrow \infty } \left\{ \sum _ { i = 1 } ^ { n } \left[ \sqrt { 4 - \left( \frac { 2 i } { n } \right) ^ { 2 } } \right] \frac { 2 } { n } \right\}$ then fine the limit.