#### Answer

$(11, 17, 20)$ is NOT a Pythagorean Triple

#### Work Step by Step

The longest side is always the hypotenuse. $c=20$
Using the Pythagorean Theorem...
$a^{2}+b^{2}=c^{2}$
$11^{2}+17^{2}=20^{2}$
Simplify...
$121+289=400$
$410\ne400$
Since the equation is not true, the numbers $(11, 17, 20)$ are NOT a Pythagorean Triple.