#### Answer

Acute Triangle

#### Work Step by Step

Using the Pythagorean Theorem...
$a^{2}+b^{2}=c^{2}$
$4^{2}+5^{2}=6^{2}$
Simplify...
$16+25=36$
$41=36$
Since the sum of the sides squared $(41)$ is greater than the hypotenuse squared $(36)$, the triangle is an acute triangle.