Chapter 3 - Section 3.4 - Real Zeros of Polynomials - 3.4 Exercises - Page 285: 100

$35ft\times57ft$

Using Pythagorean Theorem, the other side length is given by $\sqrt {(x+10)^2+x^2}$ and the know area is $x\sqrt {(x+10)^2+x^2}=5000$ $2x^2+20x+100=\frac{25000000}{x^2}$ $2x^4+20x^3+100x^2-25000000=0$ Solving the equation numerically gives $x\approx57ft$ and the other side can be calculated as $35ft$