N-4-9
When simplifying

You’re gonna use the midpoint formula to find the radius: (1+7/2, 2-6/2) and get (4,-2). Now you use the distance formula to find the radius which would be √(1-4)^2 + (2-(-2)^2 and get 5 (√= square root of). Now you plug that into the circumference equation C= 2 x pi x 5 and get 31.4 units. Sorry that took me so long and hope this helps you out!!