If the sides of a triangle have lengths a, b, and c, and c^2=a^2+b^2, then the triangle is a right triangle.
This tells us that we can use the Pythagorean Theorem in reverse to test if a triangle is right. In general, the hypotenuse c has the greatest value. Notice that in our exercise the greatest value is 4sqrt(19).
Let's substitute the side lengths of this triangle into a^2+b^2=c^2, and see if they produce a true statement.
