4. B
5. B
6. D
Explanation:
4. The radius is 3 units (3 boxes). So you do pi*r^2 = 3.14*9
5. You want the area of the box minus the area of the two circles.
Height of the box is 8 (bottom of circle to the top is two times the radius). Width of the box is 16 (left end of the left circle to the right end of the right circle) so 4 times the radius of the circles. Area of box is 128
Area of each circle is 3.14*(16). So you do 128 - 2*3.14*16.
6. Just plug in the radius 9 to the area of a circle formula: pi*radius^2 = 81*pi