Question

which equation would you use to solve for x?
$13^2 + x^2 = 5^2$
$x^2 + 5^2 = 13^2$
$5^2 + 13^2 = x^2$

Explanation:

Step1: Recall Pythagorean theorem

For a right triangle, $a^2 + b^2 = c^2$, where $c$ is the hypotenuse (longest side, opposite the right angle).

Step2: Match sides to the theorem

Here, hypotenuse $c=13$ m, legs $x$ and $5$ m. Substitute into theorem:
$x^2 + 5^2 = 13^2$

Answer:

$\boldsymbol{x^2 + 5^2 = 13^2}$ (the equation in the purple box)