#### Answer

3$\sqrt 2$

#### Work Step by Step

The Pythagorean Theorem says that $(leg_{1}) ^{2}$+$(leg_{2})^{2}$=$hypotenuse^{2}$.
This formula is more commonly referred to as $a^{2}$+$b^{2}$=$c^{2}$
You are given the lengths of both legs as x and the length of the hypotenuse as 6. Substitute x in for a and b and 6 in for c.
$a^{2}$+$b^{2}$=$c^{2}$
$x^{2}$+$x^{2}$=$6^{2}$
2$x^{2}$=36
Divide both sides by 2.
$x^{2}$=18
Take the square root of both sides to find the length of the missing side.
a=b=3$\sqrt 2$