Revision Notes of Chapter 13 Surface Areas and Volumes Class 9th Math
Topics in the Chapter- Basic Revision
- Formula for Cuboid
- Formula for Cube
- Formula for Right Circular Cylinder
- Formula for Right Circular Cone
- Formula for Sphere
- Formula for Hemisphere
- Tips and Notes
- The bodies occupying space are called solids, such as a cuboid, a cube, a cylinder, a cone, a sphere, etc. These solids have plane or curved surfaces.
- The outer surface of a cuboid is made up of six rectangles. If we take the length of the cuboid as â„“, breadth as b and the height as h, then Surface area of a cuboid = 2[lb + bh + hl]
- The cuboid whose length, breadth and height are equal is called a cube. Let each edge of the cube be ‘a’, then Surface area of a cube = 6a2
Curved Surface Area for Cuboid or Area of four walls = 2(bh + hl) = 2(l + b) × h
Total Surface Area for Cuboid = 2(lb + bh + hl)
Volume for Cuboid = l×b×h
Formula for Cube
Curved Surface Area for Cube or Area of four walls = 4l2
Total Surface Area for Cube = 6l2
Volume for Cube = l3
Formula for Right Circular Cylinder
Curved Surface Area for Right Circular Cylinder = 2Ï€rh
Total Surface Area for Right Circular Cylinder = 2Ï€r(r + h)
Volume for Right Circular Cylinder = πr2h
Formula for Right Circular Cone
Slant height of right Circular Cone: 
Curved Surface Area for Right Circular Cone = πrl
Total Surface Area for Right Circular Cone = πr(r + l)
Volume for Right Circular Cone = 1/3 (Ï€r2h)
Formula for Sphere
Curved Surface Area for Sphere = 2Ï€rh
Total Surface Area for Sphere = 2Ï€r(r + h)
Volume for Sphere = πr2h
Formula for Hemisphere
Curved Surface Area for Hemiphere = 4Ï€r2
Total Surface Area for Hemiphere = 4Ï€r2
Volume for Hemiphere = 4/3(Ï€r3)
Tips and Notes
- Area × Rate = Cost
- Density = Mass/Volume
- 1 m3 = 1000 litres
- 1 L = 1000 cm2
- Speed = Distance/Time
- 1 km = 1000 m = 105 cm
- 1 km2 = 106 m2
- 1 m = 100 cm
- 1 m2 = 10000 cm2
- 1 km/hr = 5/18 m/sec
- 1 km/hr = 50/3 m/min
- Shape of the river = cuboid