A 13 ft ladder is leaning on a tree is on the ground at a distance of 5 ft from the base of the tree. what is the distance, in feet, between the ground and the top of the ladder.

You use pythagorean's theorem. 13 squared equals 169 and 5 squared equals 25. You then take the hypotenuse, 169, and subtract one of the legs, 25, to get 169-25 = 144. You take the square root of that and get 12 ft.

13^2=5^2+X^2

169=25+X^2

144=X^2

X=12