Question 34876
A 15ft ladder is leaning against a buliding. If the bottom of the ladder is 9ft from the base of the building, how high does the ladder reach?

Draw the picture:
The ladder is the hypotenuse of a right triangle.
The 9 ft. is one of the sides.
Let the height the ladder reaches be "x".
EQUATION:
 x^2+9^2=15^2
 x^2=144
 x=12 ft. (the ladder reaches 12 ft. up the wall)
Cheers,
Stan H.