A **cylinder** can be considered as lots of circular discs stacked one above the other.

If the area of each circular disc is A and the height of the stack is h, then the volume = Ah.

Remember that the **area of a circle** is** πr ^{2}** where r is the radius of the circle.

So the volume of a cylinder with radius r and height h =** π x r ^{2} x^{ }h **or as

**πr**

^{2}h

**Example**

Find the volume of this cylinder in cm^{3} to 3 significant figures.

**Answer**

Diameter = 6 cm

Radius = 6 ÷ 2 = 3 cm

Height = 12 cm

**Volume **= πr^{2}h = π × 3^{2} × 12 = π x 9 x 12 = 339.29 ≈ **339 cm ^{3 }**(3 s.f.)

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