Aladder leans against a wall. the end of the ladder touches the wall 12m from the ground. the foot of the ladder is 9m away from the foot of the wall. what is the length of the ladder?

Check the picture below.

  15 m

Step-by-step explanation:

The Pythagorean theorem tells you the length of the hypotenuse of a right triangle is the root of the sum of the squares of its legs. Here, the ladder forms the hypotenuse of a triangle with legs 9 m and 12 m, so has length ...

  length = √((12 m)² +(9 m)²) = √(144+81) m = 15 m

The ladder is 15 m long.