The length of an arc is the fraction of its circumference based on the given intercepted angle. This is given by the equation,
L (arc) = (Angle / 360) x 2πr
Substituting the known values,
L (arc) = (40 / 360) x 2π(8 inch) = 16π/9 inch
Thus, the length of the arc is approximately equal to 5.585 inches.