Circle A: 25.12 = pi*8. If you divide both sides by 8, you will get 3.14=pi.
Circle B: 9.42 = pi*3. If you divide both sides by 3, you will get 3.14=pi.
Part B: A=pi*r^2
Circle A: 50.24=pi*4^2 (since r=d/2, r=8/2=4). Simplify the exponent to get 50.24 = 16*pi. Divide by 16 and get 3.14 = pi.
Circle B: 7.065 = pi*(1.5)^2 (since r=d/2, r=3/2=1.5). Simplify the exponent to get 7.065 = 2.25*pi. Divide by 2.25 and get 3.14 = pi.
Although the values of the area and circumference are different, when you solve for pi, the answer is the same. It does not matter how big or small of a circle you are talking about, the value of pi will remain constant.