Menelaus

Menelaus' theorem is a principle in geometry that relates the angles and lengths in a triangle when a transversal line crosses its sides or their extensions. Specifically, if a line intersects the sides (or their extensions) of a triangle, the theorem provides a relationship between the segments it creates. It states that the product of certain pairs of these segment lengths, considering their directions, equals one. This theorem is useful for solving problems involving the ratios of segments on a triangle’s sides and understanding how a line interacts with the triangle’s geometry.