Question

Observe the diagram and write which sentence is true.


(1) [l (MN)]² + [l (LN)]² = [l (ML)]²
(2) [l (MN)]² + [l (ML)]² = [l (LN)]²
(3) [l (ML)]² + [l (LN)]² = [l (MN)]²

Answer 1

(2) [l (MN)]² + [l (ML)]² = [l (LN)]² is true.
In a right triangle, side opposite to the right angle is called hypotenuse.
∆LMN is right-angled at M.

By Pythagoras theorem,
(Hypotenuse)² = (side one)² + (side two)²
∴ [l (MN)]² + [l (ML)]² = [l (LN)]²