An aircraft hangar is semi-cylindrical, with diameter 40m and length 50 m. A helicopter places an inelastic rope across the top of the hangar and one end is pinned to a corner, a A. The rope is then pulled tight and pinned at the opposite corner, B. Determine the lenghth of the rope.
So, first I find the diagonal line from A straight to B.
The answer is 64.03124......
Then, I find out that there is a semi-circle shape. So I find the length of the arc.
r=32.05162....... Length=2*Pi*32.05162..... =201.16008m......
But the correct answer is 80.30m
Can anyone tell me where i did wrong?