Step 1: Note down the given data and construct a triangles using the given data


Given that ΔABC is an isosceles triangle right angled at C.

In ΔACB, ∠C = 90°

Step 2: Make a use of the given hints.

            GIVEN:  ABC is an isosceles triangle

            So, AC = BC

Step 3: Apply the Pythagoras theorem.

             AB^2 = AC^2 + BC^2 ([By using Pythagoras theorem]

                       = AC^2 + AC^2  [Since, AC = BC]

             AB^2 = 2 AC^2   

          Hence, proved