How to Solve Mensuration (3D Shapes) — Step by Step Guide
Volume and surface area of cube, cuboid, cylinder for Class 8. This guide covers Class 8 to 8.
Step-by-Step Method
- 1
Cube: Volume = a³, TSA = 6a², LSA = 4a².
- 2
Cuboid: Volume = l × b × h, TSA = 2(lb + bh + hl), LSA = 2h(l + b).
- 3
Cylinder: Volume = πr²h, TSA = 2πr(r + h), CSA = 2πrh.
- 4
Always identify what is being asked — volume, total surface area, or lateral/curved surface area.
- 5
Convert all measurements to the same unit before calculating.
Worked Example
Problem: Find the volume of a cuboid with dimensions 10 cm × 5 cm × 4 cm.
Solution: Volume = 10 × 5 × 4 = 200 cm³.
Common Mistakes to Avoid
- ✗
Confusing lateral/curved surface area with total surface area.
- ✗
Using diameter instead of radius in cylinder formulas.
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Not converting between cm³ and litres (1 litre = 1000 cm³).
- ✗
Forgetting the two circular faces when calculating TSA of a cylinder.
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Frequently Asked Questions
- How do I solve Mensuration (3D Shapes) problems?
- Cube: Volume = a³, TSA = 6a², LSA = 4a². Cuboid: Volume = l × b × h, TSA = 2(lb + bh + hl), LSA = 2h(l + b).
- What are common mistakes in Mensuration (3D Shapes)?
- Confusing lateral/curved surface area with total surface area. Using diameter instead of radius in cylinder formulas.
- Which class covers Mensuration (3D Shapes)?
- Mensuration (3D Shapes) is typically taught in Class 8. SparkEd has free practice for all these grades.
- Where can I practise Mensuration (3D Shapes) for free?
- SparkEd offers free chapter-wise practice for Mensuration (3D Shapes) aligned to CBSE, ICSE, and IB curricula. Visit sparkedmaths.com to start.
SparkEd Maths — sparked.coms@gmail.com — www.sparkedmaths.com