Solving Pythagoras Problem 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. 
c^2=50^2+40^2
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?


This question is a simple Pythagoras problem.
 First, we find the length of the arc whose diameter is 40m.
Then we assume it to be a side of the quadrilateral whose side is 50 m.
Next, we use Pythagoras theorem to find the diagonal.
The answer will be near to 80.34..
