Answer:
12 foot.
Step-by-step explanation:
Given that,
A ladder leans a 15 foot ladder against a second story window.
The distance on the ground between the base of the ladder and the house is 9 feet.
We need to find the height of the ladder. Let it is h.
If we consider a right angles triangle such that 15 foot is hypotenuse, 9 feet is base, then we need to find the perpendicular height of the triangle. Using Pythagoras theorem to find it.
[tex]15^2=9^2+h^2\\\\h^2=15^2-9^2\\\\h^2=225-81\\\\h=12\ \text{foot}[/tex]
So, the height of the ladder that reaches the second story window is 12 foot.
