First, determine the circumference (C) of the circle, the equation, C = 2πr Substituting the value or the radius, C = 2π ( 4) = 8π The arc length is the product of the circumference and the ratio between the subtended angle and 360. The mathematical expression is already, S = (8π) x (72 / 360) = 0.8π Thus, the arc is 0.80π.
