A 20 foot ladder is leaned against a house and the base of the ladder is 4 feet from the house. How far up does the ladder reach?

Answer:
20.40 ft
Step-by-step explanation:
a^2 + b^2 = c^2 (right triangle) (sides of the triangle are the house and the distance from the base of the ladder to the house. The hypotenuse is the ladder.
20^2 + 4^2 = c^2
400 + 16 = c^2
C = sqrt 416
C = 20.40 ft