Class 8 Maths – Chapter 11

Mensuration

STEP 2: Formula Sheet

📐 Formulas for 2D Shapes

Square:

Perimeter = 4 × side

Area = side × side

Rectangle:

Perimeter = 2 × (length + breadth)

Area = length × breadth

Triangle:

Area = ½ × base × height

Circle:

Circumference = 2πr

Area = πr²

📦 Formulas for 3D Shapes

Cuboid:

LSA = 2h(l + b)

TSA = 2(lb + bh + hl)

Volume = l × b × h

Cube:

LSA = 4a²

TSA = 6a²

Volume = a³

Cylinder:

CSA = 2πrh

TSA = 2πr(r + h)

Volume = πr²h

📏 Units Reminder

• Area → square units (cm², m²)
• Surface Area → square units
• Volume → cubic units (cm³, m³)

🎯 Exam Tip

Always write the formula first, substitute values clearly and then calculate. This method ensures full marks.