In a circle, the circumference and the radius are related by pi as per th is formular: C = 2*pi*r. Then, in this case 42 inches = 2*pi*r and you can solve for r. r = 42 inches / (2*pi) = 42 / (2*3.14159) = 6.6845, which rounded to the nearest hundredth is 6.68.