Class 8 · Chapter 11

Mensuration

Area of trapezium, general quadrilateral; surface area and volume of cube, cuboid, cylinder.

Watch this chapter

Read the full chapter

Tip: open the NCERT PDF for the original chapter text alongside the notes here.

Detailed theory

Area

= \tfrac{1}{2}\cdot(a+b)\cdot h

where

a, b

are parallel sides and

h

is the perpendicular distance.

Key concepts & formulas

Area of trapezium

= \tfrac{1}{2}(a+b)\cdot h

Volume of cuboid

= l\cdot b\cdot h

; cube

= a^3

Volume of cylinder

= \pi r^2 h

TSA of cube

= 6a^2

TSA of cylinder

= 2\pi r(r+h)

; CSA

= 2\pi r h