How to Find the Length of a Circle
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How many sides does a polygon have to have before the perimeter is almost equal to a cirlce passing through each corner? |
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Notice how quickly the perimeter of the polygon and the cirlce become almost equal. π = 3.1415926535 8979323846 2643383279 5028841971....... see http://www.joyofpi.com/pi.html for more digits!!! |
Unroll a Circle
Rotate the circle to unroll the circumference. You can also change the radius of the circle.
[size=150]Pi is the ratio of the circumference of the circle to the diameter. [br]How many times does the radius "fit" into the circumference?[br]How many times does the diameter "fit" into the circumference?[br]what happens when you increase or decrease the radius?[/size]
[size=100][size=150]The radian is an alternative unit for measuring angles. It is useful when studying circular motion as the length of an arc can be easily found from an angle in radians.[br][br][math]\theta=\frac{s}{r}[/math] where [i]s[/i] is length of an arc marked out by the angle [math]\theta[/math] and [i]r is the radius of the circle.[/i][/size][/size]