A circle and a point in unicode
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HTML + CSS gold circle
http://jsfiddle.net/m9TLb/1/
"A circle is a square with rounded corners"

a circle
a point
a line

all perfect

draw a straigth line and follow it

A classic:
http://www.videobash.com/video_show/teacher-draws-a-perfect-circle-389305

http://en.wikipedia.org/wiki/Circle#mediaviewer/File:Circle-withsegments.svg


Using the same tools as on paper: A cup to guide for the circle, a pen to guide for the line, smashing the pen to the paper for the point.

http://i.imgur.com/7QI1BFm.png



Python turtle module

import turtle
def circle(n,x):
    angle=360/n
    for i in range(n):
        turtle.forward(x)
        turtle.left(angle)

print circle(360,1)



