HL (Hypotenuse-Leg)

The HL (Hypotenuse-Leg) theorem is a rule used to determine if two right triangles are congruent, meaning they are identical in shape and size. It states that if two right triangles have one matching hypotenuse (the longest side opposite the right angle) and one matching leg (one of the sides that form the right angle), then the triangles are exactly the same. Essentially, knowing these two measurements is enough to confirm that the triangles are congruent, without needing to compare all sides and angles.