Since the flagpole makes a 90 degree angle to the ground, the height is 15 feet tall and the length of the triangle is 20 feet long. You can use the Pythagorean theorem to find out “c”, but since this is a “3,4,5” triangle, you multiply 5 by 5 to get 25, which is the hypotenuse. Therefore, 25 feet is the answer. •hope this helps!•