## 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

**Basics Revision**

- 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 = 6a
^{2}

**Formula for Cuboid**

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 = 4l

^{2}
Total Surface Area for Cube = 6l

^{2}
Volume for Cube = l

^{3}**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 = Ï€r

^{2}h**Formula for Right Circular Cone**

Slant height of right Circular Cone:

Curved Surface Area for Right Circular Cone = Ï€rl

Total Surface Area for Right Circular Cone = Ï€r(r + l)

Volume for Right Circular Cone = 1/3 (Ï€r

^{2}h)**Formula for Sphere**

Curved Surface Area for Sphere = 2Ï€rh

Total Surface Area for Sphere = 2Ï€r(r + h)

Volume for Sphere = Ï€r

^{2}h**Formula for Hemisphere**

Curved Surface Area for Hemiphere = 4Ï€r

^{2}
Total Surface Area for Hemiphere = 4Ï€r

^{2}
Volume for Hemiphere = 4/3(Ï€r

^{3})

**Tips and Notes**

- Area × Rate = Cost
- Density = Mass/Volume
- 1 m
^{3}= 1000 litres - 1 L = 1000 cm
^{2} - Speed = Distance/Time
- 1 km = 1000 m = 10
^{5}cm - 1 km
^{2}= 10^{6}m^{2} - 1 m = 100 cm
- 1 m
^{2}= 10000 cm^{2} - 1 km/hr = 5/18 m/sec
- 1 km/hr = 50/3 m/min
- Shape of the river = cuboid