Converse of Pythagorean Theorem: If c² < a² + b², triangle ABC is acute; if c² = a² + b², it is a right triangle; if c² > a² + b², it is obtuse.
Diagram illustrating the Converse of the Pythagorean Theorem with three triangles showing conditions for acute, right, and obtuse triangles based on side lengths a, b, and c.