(a) The square
For all rectangles, the area is the length multiplied by the height. For squares (a special type of rectangle), the length and height are the same, so you just use
, where
is the side length.
(b) The circle
The formula for the area of the circle is
, where
is pi, a constant, and
is the radius of the circle, or the length from the center point to the edge.
We're given the side length of the square, which is the same as the diameter of the circle (length from edge to edge going through the center point). Divide the diameter by
to get the radius of
kilometers.
(c) The blue section
The area of the blue section is simply the area of the square minus the area of the circle since we just want what's left over.
You can keep the answer exact (the boxed expression) or use the approximate value of 54.9, depending on the instructions for the assignment.