Circle Perimeter Formula The circumference of a circle

Circle Perimeter Formula The circumference of a circle Click the mouse 1

Click the mouse only when you see Click the mouse or Click to see If you click too soon you will miss the best bits. Click the mouse 2

The circumference of a circle Click the mouse 3

First we need What is ? (pi) Is it a number? Is it…. . 3. 14159265358979323846264338 327950288419716939937510582097 494459230781640628620899862803 482534211706798214808651328230 66470938446095505822172535…. . ? Click the mouse 4

Well… not exactly. is a ratio. Click the mouse 5

Pi is the number of times you must travel straight across the circle to go the same distance as all the way round the circle. Click to see the paths Once across twice across three times across and a bit further! So is a bit more than 3. Click the mouse 6

How can we be sure that is a bit more than 3? 3 2 1 For a regular hexagon, the distance all the way round is exactly 3 times the distance straight across the middle. Click to see the paths Click the mouse 7

And all the way round the circle is a little bit more than all the way round the hexagon. So all the way round the circle Click to see the paths is a little bit more than 3 times straight across the middle. Circumference = × Diameter Click the mouse 8

Summary Circumference = × Diameter Click the mouse 9