Mensuration
Circles, trapeziums, cuboids and cylinders.
Learn with Kutty
Go one screen at a time. Press Next when you are ready. Tap 🔊 Read to me to listen.
Each shape has a rule for its area (flat space) and volume (space inside).
Look: A cylinder: a circle stacked up to height h.
✏️ Your turn!
Type your answer and press Check. Kutty will tell you if it is right.
1Around a circle with diameter 14 cm (π = 22/7)?
2Cylinder: r = 7 cm, h = 10 cm. Volume?
3Cube with 4 cm sides. Surface area?
! Careful!
✗Using the diameter in πr².
✓Halve it first: radius = diameter ÷ 2.
✗Mixing m and cm.
✓Change to the same unit first.
See the whole lesson on one page
Each shape has a rule for its area (flat space) and volume (space inside).
Circle: area = πr², around = 2πr. Cylinder: volume = πr² × height. π is about 22/7 or 3.14.
Think of it like thisA tin can is a stack of coins (circles). Its volume is the area of one circle times the height of the stack.
- π
- About 3.14: how many times the width fits around a circle.
Solved together
A circle has radius 7 cm. What is its area? (π = 22/7)
Area = π × r × r.
22/7 × 7 × 7Cancel the 7s, then multiply.
22 × 7 = 154
AnswerArea = 154 cm².
Now practise it
Kanakku makes new questions on mensuration every time. It shows the working and gives a hint when you are stuck.