Correct Answer - Option 3 : 12√2 cm

**Given:**

Length of rectangle = 6 cm

Breadth of the rectangle = 24 cm

Area of rectangle = Area of square

**Concept:**

Area of rectangle = (l × b) cm^{2}

Area of square = (a × a) cm^{2}

Diagonal of square = √2 a cm

**Calculation:**

Area of rectangle = (6 × 24) cm^{2} = 144 cm^{2}

Area of square = 144 cm^{2}

∴ Side of the square = √144 = 12 cm

∴ Diagonal of the square = √2 × 12 = 12√2 cm