Question

A firefighter places a 29 feet ladder, so that the base of the ladder is 21 feet from the wall. What is the height at which the top of the ladder touches the wall?

Answer 1

Pythagorean theorem:
a^2+b^2=c^2 (C^2 always is the hypotenuse)

21^2+b^2=29^2
441+b^2=841
841-441=400
square root of 400 is 20
Your answer is 20