The diagram below shows a telephone pole outside of Roger's house. The pole is 20 feet high and the cable between the pole and the ground is 25 feet. What is the distance between the stake, which is holding the cable in the ground, and the base of the pole?

Answer 1

Use the Pythagorean Theorem.
Or recognize this as a 3-4-5 right triangle, just scaled up by a factor of 5.