So the formula for area of a circle is A=πr^2 We know that the diameter (or distance across) one blue half-circle is 40 yards And radius is half of the diameter so 40/2 = 20 so radius=20 Now just plug it into the equation! A = π (20)^2 —> A = π (400) —> A = 1256 BUT that is the equation to find area of a complete circle. Since this is a HALF circle, divide that area in half: 1256/2 = 628 So the area of one of the blue half-circles is 628
