# Facts that Matter: Surface Areas and Volumes Class 9 Notes | EduRev

## Class 9 : Facts that Matter: Surface Areas and Volumes Class 9 Notes | EduRev

The document Facts that Matter: Surface Areas and Volumes Class 9 Notes | EduRev is a part of the Class 9 Course Class 9 Mathematics by VP Classes.
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Facts that Matter

• Total surface area of a cuboid = 2[ℓb + bh + ℓh]
• Total surface area of a cube = 6(side)2
• Lateral surface area of a cuboid = Area of walls of  a room = 2(ℓ + b) x h
• Lateral surface area of a cube = 4a2
• Curved surface area of cylinder = 2πrh
• Total surface area of a cylinder = 2πr(r + h)
• Curved surface area of a cone = πrℓ
• Total surface area of a cone = πr(r + ℓ)
• Surface area of a sphere = 4πr2
• Curved surface area of a hemisphere = 2πr
• Total surface area of a hemisphere = 3πr2
• Volume of a cuboid = ℓ x b x h
• Volume of a cube = (side)3
• Volume of a cylinder = πr2h
• Volume of a cone = • Volume of a hemisphere = .
• Volume of a sphere = • 1000 cm3 = 1 litre

SOLIDS AND THEIR SURFACE AREAS
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.

SURFACE AREA OF A CUBOID AND A CUBE
The outer surface of a cuboid is made up of six rectangles. If we take the length of the cuboid as ℓ, breadth as b and the height as h, then Surface area of a cuboid = 2[lb + bh + hl]
Let us recall that a 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

Note:
I. Sometimes a cuboid does not have bottom and top faces. In such cases the area of four facesis called the lateral surface area.
II. Lateral surface area of a cuboid is 2(ℓ + b)h.
III. Lateral surface area of a cube is 4a2.
IV. Surface area of a cuboid or cube means total surface area.

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