The area of the entire circle = pi r^2 The area of the shaded area = (40/360) * pi r^2 r = 9 cm
Area of the shaded area = 1/9 * 3.14 * 9^2 Area of the shaded area = 3.14 * 9 Area of the shaded area = 28.26
Notice one of the 9s disappeared. Where did it go? You could begin the problem by writing out 9^2 Area = 1/9 * 3.14 * 9 * 9 Notice that 1/9 will cancel out 1 of the nines.
