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Learn how to calculate the circumference and area of a circle. Understand the concept of pi and its relationship to the circle's measurements. Follow the interactive tutorial by Tandi Clausen-May for step-by-step explanations.
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Circle Formulae 1 The circumferenceof a circle Tandi Clausen-May Click the mouse
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 Click the mouse
The circumference of a circle Click the mouse Tandi Clausen-May
First we need (pi) Is it….. 3.14159265358979323846264338 327950288419716939937510582097 494459230781640628620899862803 482534211706798214808651328230 66470938446095505822172535…..? What is? Is it a number? Click the mouse
Well… not exactly. is a ratio. Click the mouse
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
How can we be sure that is a bitmore 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
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 is a little bit more than 3 times straight across the middle. Click to see the paths Circumference =× Diameter Click the mouse
Summary Circumference = × Diameter Click the mouse
Circle Formulae 2 Now watch The areaof a circle Tandi Clausen-May