Instructables
Picture of Circumference of a Circle
Have you always wanted to know how to find the circumference of a circle? Have you always wanted to impress your friends by telling them the length of the outer boundary of your bicycle wheel? Have you always had an intense desire to order a pizza by its perimeter rather than by simply saying 'small' 'medium' or 'large'? Well, my friend, today is your lucky day because I am here as the mathmatical genie, ready to grant your three wishes in regards to the circumference of a circle. Thats right, and all for free. But wait! Read this instructable within the next three minutes and I will include a free example of how to find the circumference of a pizza! (Please note, pizza is not included.)
 
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Step 1: Getting associated with the circle.

Picture of Getting associated with the circle.
This, again, is a circle. The "r" in the circle is the radius. The radius will be vital in our adventure to find the circumference of the circle.
r stands for radius, and radius stands for Really important.
Remember, radius really really is relevant.
ARGHHHHH!
Have you ever heard of diameter? Who needs diameter? Diameter is for fools.
Well you could use diameter, but then I won't be able to give you the neato way to remember the circumference equation in the next step (by the way, diameter is just radius multiplied by 2.)

To find the radius, measure from one point on the circle to the opposite side from that point using a ruler, that length is your diameter, divide that by two and BAM you've got yourself a pretty little radius.

Remember: 2r=D
thank you you help me alot
JakeTobak5 years ago
I was gonna ask what a circle is, but your first step (intro actually) covered it. Well done.