Question 549188
Imagine a right triangle in which the distance from the base of the ladder to the wall is its base and the ladder is its hypotenuse (c). The height (a) would be the 12 feet up the wall.
You need to find the the length of the base (b).
Use the pythagorean theorem:
{{{c^2 = a^2+b^2}}} Solve for b.
{{{b = sqrt(c^2-a^2)}}} Substitute c = 15 and a = 12
{{{b = sqrt(15^2-12^2)}}}
{{{b = sqrt(225-144)}}}
{{{b = sqrt(81)}}}
{{{b = 9}}}feet.