A triangle has side lengths of 34 in., 28 in., and 42 in. Is the triangle acute, obtuse, or right?

The type of triangle may be known by determining the relationship between the sum of the squares of the two shorter sides to the square of the third side. From the given,

(34 in) ² + 28 in² = 1940; (42 in) ² = 1764 in²

1940 > 1764

From the derived relationship above, the triangle is obtuse.