Radius r = 3inches
Arc A = 8 inches
We need formula that connects lenght of arc with central angle. That one is fallowing one:
A = 2*r*pi*α/360 where α is central angle. we can see that if α=360, A = 2*r*pi which is exactly the formula for parimeter of circle.
Further more we can express 360 in radians which is 2* pi and get
A = r*α as simpler formula
α = A/r = 8/3 = 2.66666667 ≈ 2.7
