It’s not possible to form a right triangle with the lengths of 2, 4, and 7 because you can’t even form a triangle in the first place with these three values. For a triangle to be a triangle, the sum of the two smaller side lengths have to be greater than the longest side length. In this case, 2+4=6 and 6 is not greater than 7. These side lengths cannot form a right triangle; granted a triangle in the first place.
