Answer:
B. 12 ft
Explanation:
We can see from the image that a right-angled triangle is formed by the ladder, the side of the house, and the ground.
We can use the Pythagorean Theorem to determine how far from the base of his house he should place the ladder as shown below;
[tex]\begin{gathered} 20^2=x^2+16^2 \\ 400=x^2+256 \\ 400-256=x^2 \\ 144=x^2 \\ \sqrt[]{144}=x \\ 12=x \\ x=12ft \end{gathered}[/tex]
