Mensuration Notes
Table of Contents
Mensuration
➥ Mensuration is the branch of mathematics that deals with the measurement of geometric figures like 2D shapes (areas) and 3D objects (surface area and volume).
Important Terms in Mensuration
- Perimeter: The total length of the boundary of a closed figure.
- Area: The space enclosed within a 2D shape.
- Volume: The space occupied by a 3D object.
- Lateral/Curved Surface Area (LSA/CSA): The area of all the sides of a 3D object excluding the top and bottom.
- Total Surface Area (TSA): The total area covered by the outer surfaces of a 3D object.
Mensuration Formulas
2D Shapes
Shape | Area | Perimeter | Diagonal | Diagram |
---|---|---|---|---|
Square | Side2 | 4 × Side | √2 × Side | |
Rectangle | L × B | 2 × (L + B) | √(L2 + B2) | |
Triangle | ½ × Base × Height | Sum of all sides | N/A | |
Circle | Ï€r2 | 2Ï€r | √(2 × r2) | |
Semi-Circle | ½ × Ï€r2 | Ï€r + 2r | √(r2 + r2) |
3D Shapes
Shape | Volume | Curved Surface Area (CSA) | Total Surface Area (TSA) | Diagram |
---|---|---|---|---|
Cube | Side3 | 4 × Side2 | 6 × Side2 | |
Cuboid | L × B × H | 2(LB + HL) | 2(LB + BH + HL) | |
Cylinder | πr2h | 2πrh | 2πr(r + h) | |
Cone | ⅓Ï€r2h | Ï€rl | Ï€r(r + l) | |
Sphere | 4/3Ï€r3 | N/A | 4Ï€r2 | |
Hemisphere | 2/3Ï€r3 | 2Ï€r2 | 3Ï€r2 |
Difference Between 2D and 3D Shapes
Feature | 2D Shapes | 3D Shapes |
---|---|---|
Definition | Have only length and breadth. | Have length, breadth, and height. |
Area/Volume | Only area is measured. | Both surface area and volume are measured. |
Example | Square, Triangle, Circle | Cube, Cylinder, Sphere |
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