A cable 20 meters long is attached to the top of a telephone pole. The cable is just able to reach a point on the ground 12 meters from the base of the telephone pole. Find the height of the telephone pole.

Solution:

  (Height of the pole)2 = (length of cable)2 - (distance between pole and the point in the ground)2   

                                    = 202 - 122 

                                    = 400 - 144 = 256

 Height of the pole = √256 = 16 meters