The situation forms a right triangle:
Since it's a right triangle, we can apply the Pythagorean theorem:
c^2 = a^2 + b^2
where:
c= hypotenuse (the longest side ) = 17
a & b = the other 2 legs of the triangle:
Replacing:
17^2 = 8^2 + x^2
Solve for x (the distance between the ladder and the bottom of the slide)
289 = 64 + x^2
289-64 = x^2
225 = x^2
√225 = x
15 = x