For triangle SUN to be a right angle triangle the square root of the sum of the squares of the adjacent sides should equal
the hypotenuse, whose length should be larger than any of the sides. Therefore in this problem 7 is the larger length and should be the hypotenuse, and 5 and 6 should be the lengths of the other two sides. Calculating:
√( 52+62) = √(25+36) = √61=7.82 ≠ 7 , Therefore this is not a right angle triangle based on the Pythagorean theorem.