A Rectangle Is Bounded by the X-Axis and the Semicircle $y = \sqrt { 49 - x ^ { 2 } }$

Multiple Choice

A rectangle is bounded by the x-axis and the semicircle $y = \sqrt { 49 - x ^ { 2 } }$ (see figure) .Select the area A of the rectangle as a function of x, and determine the domain of the function.

A) $A ( x ) = 2 | x | \sqrt { 49 - x ^ { 2 } }$ , -7 $\le$ x $\le$ 7
B) $A ( x ) = - 2 x \sqrt { 49 - x ^ { 2 } }$ , -7 $\le$ x $\le$ 7
C) $A ( x ) = x \sqrt { 49 - x ^ { 2 } }$ , x $\ge$ 0
D) $A ( x ) = 2 x \sqrt { 49 - x ^ { 2 } }$ , x $\ge$ 0
E) $A ( x ) = | x | \sqrt { 49 - x ^ { 2 } }$ , all real numbers