No
Explanation:
For a triangle to have a right angle the square sums of the legs have to equal the square of the hypotenuse.
In this case 9 is the hypotenuse which is the longest side in a triangle. 5 and 7 are the two smaller sides which make them the legs.
Putting this set of numbers into the pythagorean theorem is the way to solve this.
5²+7² should equal 9² if the triangle is a right triangle.
Solve the squares: 25+49=81
This would add up to be 74 and that is not equal to 81, so by this statement we can conclude that 5, 7, and 9 do not make a right triangle.