a telephone pole breaks and falls as shown. to the nearest foot, what was the original height of the pole? 12ft and 5ft are the sides

Assuming that a=5, b=12 
then this triangle is clearly in the 
 
family of right triangles. And since the broken part has to be the hypotenuse, the original length had to be the shortest side and hypotenuse: 

 
l=18ft