http://www-history.mcs.st-and.ac.uk/Curves/Circle.html

Circle. Cartesian equation: x2 + y2 = a2 or parametrically: x = a cos(t), y = a sin(t) Polar equation: r = a. Click below to see one of the Associated curves.

http://jwilson.coe.uga.edu/EMT668/EMAT6680.F99/Kim/emat6690/instructional%20unit/circle/Circle/Circle.htm

Circle. History. The study of the circle goes back beyond the recorded history. The invention of the wheel is a fundamental discovery of properties of a circle.

https://en.wikipedia.org/wiki/Circle

The circle has been known since before the beginning of recorded history. Natural circles would have been observed, such as the Moon, ...

https://circlesonly.wordpress.com/category/history-of-circles/

Posts about History of Circles written by circlesonly.

https://www.smithsonianmag.com/travel/world-full-circles-180954529/

Mar 12, 2015 ... A fascination and interest in circles predates recorded history, with many ancient cultures finding approximations for pi—the ratio of a circle's ...

https://nrich.maths.org/2561

This article for pupils gives some examples of how circles have featured in people's ... so let's explore some of the most famous and mysterious circles in history.

https://www.newworldencyclopedia.org/entry/Circle

Feb 22, 2017 ... This article is about the shape and mathematical concept of circle. For other uses of the term, see ..... History of "Circle". Note: Some restrictions ...

https://www.historytoday.com/archive/feature/man-who-invented-pi

The history of the constant ratio of the circumference to the diameter of any circle is as old as man's desire to measure; whereas the symbol for this ratio known ...

https://www.britannica.com/science/circle-mathematics

A line connecting any two points on a circle is called a chord, and a chord ... The Editors of Encyclopaedia Britannica. See Article History. Circle. Quick Facts.

https://www.wellandgood.com/good-advice/womens-circle-history-ancient/

Apr 25, 2018 ... Here, experts tell the story of women's circles past, while sharing how their ... The fascinating history behind your monthly women's circle.