Step 1: Draw a square ACDF with AC=a units. Step 2: Cut AB=b units so that BC=(a−b) unts. Step 3: Complete the squares and rectangle as shown in the diagram. Step 4: Area of yellow square IDEO= Area of square ACDF− Area of rectangle GOFE− Area of rectangle BCIO− Area of red square ABOG Therefore, (a−b)2=a2−b(a−b)−b(a−b)−b2 =a2−ab+b2−ab+b2−b2 =a2−2ab+b2 Hence, geometrically we proved the identity (a−b)2=a2−2ab+b2.