To solve this, sketch a diagram (I attached one). You will see it the wall and ladder and ground form a right triangle. Use the Pythagorean Theorem to find the base.
[tex]a^2+b^2=c^2[/tex]
[tex]a^2+4^2=5^2 \\ \\ a^2+16=25 \\ \\ a^2=9 \\ \\ \sqrt{a^2} = \sqrt{9} \\ \\ a=3[/tex]
The bottom of the ladder must be 3 feet from the base of the wall.
