Answer
The triangle is not a right triangle.
Work Step by Step
RECALL:
If the sides of a triangle satisfies $c^2=a^2+b^2$ (from the Pythagorean Theorem) where c is the hypotenuse (the longest side) and a and b are the two other sides, then the triangle is a right triangle.
Substitute the given side-lengths to obtain:
$c^2=a^2+b^2
\\7^2=4^2+5^2
\\49=16+25
\\49\ne41$
The triangle's side lengths do not satisfy the equation, so the triangle is NOT a right triangle.