Answer:
The ladder is 17 feet long
Explanation:
Let
a ----> the height of the root in feet
b ----> the horizontal distance of the base of the ladder from the house in feet
we have

To find out the how long is the ladder apply the Pythagorean Theorem
Let
c ---> the length of the ladder

where
c is the greater side (hypotenuse)
a and b are the legs
substitute the given values


therefore
The ladder is 17 feet long