I'm guessing you mean

First, compute the quotient:

Split up the remainder term into partial fractions. Notice that
<em>x</em> ² + 4<em>x</em> + 3 = (<em>x</em> + 3) (<em>x</em> + 1)
Then

So the integral becomes

We can simplify the result somewhat:

-- If FE is the longest side in the right triangle, then
the length of the missing side is 22.956... (rounded).
-- If FE is not the longest side in the right triangle,
then the length of the missing side is 25 (exactly).