Cindy is taking an archery class and decides to practice her skills at home. She attaches the target shown at right to a bale of hay. The circles on the target are concentric and equally spaced apart.
a. If the common center of the circles is located at the origin, write an equation that models the largest circle.
b. If the smallest circle is modeled by the equation x2 + y2 = 6.25, find the area of the region marked B.
