# maths circumference

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What is the circumference of a wheel with a diameter of 50cm?
πd = 3.14 × 50 = 157 cm the circumference is 157 cm or do half of the diameter (25cm) then 2 * 3.14 *25 = 157 cm
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How do you find the circumference of a circle?
If you know the diameter the circumference is pie * the diameter or 2 * pie * the radius
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How do you find the area of a circle?
Area = π r2
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If the diameter of a circle is 20 cm what is the area? (using calculator)
If the diameter is 20 cm then the radius must be 10 cm. so the area is pie * 10 * 10 = 314.159 = 312.2 cm 2
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## Other cards in this set

### Card 2

#### Front

How do you find the circumference of a circle?

#### Back

If you know the diameter the circumference is pie * the diameter or 2 * pie * the radius

### Card 3

#### Front

How do you find the area of a circle?

#### Back ### Card 4

#### Front

If the diameter of a circle is 20 cm what is the area? (using calculator)

#### Back ### Card 5

next

#### Back 