Answer: The length of the ladder is 20 feet.
Step-by-step explanation:
Given : A ladder is leaning against a building so that the distance from the ground to the top of the ladder is 8 feet less than the length of the ladder.
Mathematically,
Let x be the length of the ladder then
Distance from ground to the top of the ladder = x- 8
If distance from the bottom of the ladder to the building is 16 feet.
Since ground makes right angle with building , so the triangle made by ladder should be a right triangle.
By Pythagoras theorem of right triangle , we hae

![\Rightarrow\ x^2=(x-8)^2+16^2\\\\\Rightarrow\ x^2=x^2+64-16x+256\ [\text{Using identity :} (a-b)^2=a^+b^2-2ab]\\\\\Rightarrow 0=-16x+320\\\\\Rightarrow\ 16x=320\\\\\Rightarrow\ x=\dfrac{320}{16}=20](https://tex.z-dn.net/?f=%5CRightarrow%5C%20x%5E2%3D%28x-8%29%5E2%2B16%5E2%5C%5C%5C%5C%5CRightarrow%5C%20x%5E2%3Dx%5E2%2B64-16x%2B256%5C%20%5B%5Ctext%7BUsing%20identity%20%3A%7D%20%28a-b%29%5E2%3Da%5E%2Bb%5E2-2ab%5D%5C%5C%5C%5C%5CRightarrow%200%3D-16x%2B320%5C%5C%5C%5C%5CRightarrow%5C%2016x%3D320%5C%5C%5C%5C%5CRightarrow%5C%20x%3D%5Cdfrac%7B320%7D%7B16%7D%3D20)
Hence, the length of the ladder is 20 feet.