Question

A triangle has sides with lengths of 39 centimeters, 55 centimeters, and 62 centimeters. Is it a right triangle?

Answer 1

No. For a right triangle the squares of the two shorter sides must sum to the square of the longest side. Here the longest side is 62, and

39^2 + 55^2 = 1521 + 3025 = 4546,
62^2 = 3844.

Since 4546 ≠ 3844, the triangle is not right. (Because 4546 > 3844, the triangle is actually acute.)