Find the Center of Mass of a Thin Plate of Constant

Multiple Choice

Find the center of mass of a thin plate of constant density covering the given region.
-The region bounded by the $x$ -axis and the semicircle $y = \sqrt { 49 - x ^ { 2 } }$

A) $\bar { x } = \frac { 7 } { 3 \pi } , \bar { y } = 0$
B) $\bar { x } = 0 , \bar { y } = \frac { 7 } { 3 \pi }$
C) $\bar { x } = 0 , \bar { y } = \frac { 28 } { 3 \pi }$
D) $\bar { x } = \frac { 28 } { 3 \pi } , \bar { y } = \frac { 28 } { 3 \pi }$