1

Circle Formulae 2

The area of a circle

Tandi Clausen-May

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2

Click the mouse only when you see

or

If you click too soon you will miss the best bits.

Click the mouse Click to see

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3

The area

of a circle

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We saw in Circle Formulae 1 that…

Circumference= × Diameter

Now, what about the area?

5

Imagine a circle made out of strands of beads.

Open it out.

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6

circumference

radius (half the diameter)

Let’s watch that again.

It’s a triangle!

base = circumference

Click to see the circle open again

height = radius (half the diameter)

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7

circumference

radius (half the diameter)

= Circumference × Radius 2

Area of the triangle circle

Area of the triangle

We know how to find the area of a triangle.

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= Base × Height 2

8

= Circumference × Radius 2

Area

Summary

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9

The End

Tandi Clausen-May