You proceed from a false assumption. You, in fact, do still have a right triangle, precisely as Dru (G-spotter) points out earlier in this thread. So the Pythagorean Theorem works here, and the answer is 72.8 feet. This assumes that you are at the extreme end of the 200-foot rope, and we ignore the effects of rope stretch and the amount of rope consumed by knots.  
Note that keenwash came up with the same answer using the Law of Sines (as one would expect), but in this instance there is no need for such superfluousness in solving the problem. The more elegant solution is to invoke the Pythagorean Theorem. 
  
QED. 
  
Now to SnailEye's statement...  
 This is also true. As you ascend the rope, your distance from the wall reduces. At the halfway point (say) you will be 72.8'/2, or 36.4 feet, away from the wall (still assuming an average straight-line slope of 110 degrees). Ultimately, at the top of the rope, you are in contact with the wall.  
You can calculate how far you are from the wall at any point on the rope through the Law of Similar Triangles. LST states that for any triangles whose angles are the same, the lengths of the sides are proportional to each of the other triangles. So, at the 200-foot mark, you are 72.8 feet away from the wall. At the 100-foot mark, you are 36.4 feet away from the wall. You can see very quickly that the ratio is 200/72.8, or 2.75:1. That means that for every 2.75 feet you ascend the rope, you will hang 1 foot closer to the wall, until at the top of the rope you are touching the wall. 
  
I hope this explanation has not been too  for you. Please carry on!