The first theorems relating to circles are attributed to Thales around 650 BC. Book III of Euclid's Elements deals with properties of circles and problems of inscribing and escribing polygons. One of the problems of Greek mathematics was the problem of finding a square with the same area as a given circle.

Who is the father of circle?

Prof. Kaoru Ishikawa advocated forming “QC Circle” in order to educate and promote Quality Control for front-line workers in the workplace, on the way to realize Total Quality Control, and strived to promote it by establishing the QC Circle Headquarters, within JUSE, in 1962 for systemization.

What is the first circle theorem?

First circle theorem - angles at the centre and at the circumference. Second circle theorem - angle in a semicircle. Third circle theorem - angles in the same segment. Fourth circle theorem - angles in a cyclic quadlateral.