Let ABC be a right angled triangle in which ∠B = 90°.
Then, ∠A + ∠C = 90°
| ∵ Sum of all the angles of a triangle is 180°
∴ ∠B = ∠A + ∠C
∴ ∠B > ∠A
and ∠B > ∠C
∴ AC > BC
| ∵ Side opposite to greater angle is longer
and AC > AB
∴ AC is the longest side, i.e., hypotenuse is the longest side.
[Hint. Produce AD to E such that AD = DE and join C and E.]
OR
Prove that the sum of any two sides of a triangle is greater than twice the length of median drawn to the third side.
Prove that the sum of the three sides of a triangle is greater than the sum of its three medians.
OR
Prove that the perimeter of a triangle is greater than the sum of its three medians.