This learn node looks first in the new issue of the math and arithmetic online magazine plus where this month an article titled What is the area of a circle? uses cake slices to illustrate some principles of the geometry of a circle. The author of the circle studies is Tom Ko�ner, a lecturer in the Department of Pure Mathematical Statistics at Cambridge University. The magazine brings math explanations from terrific teachers to online visitors. The circle at the right was the work of a student in an MIT class on Geometric Combinatorics. The right circle and formulas to explain it are on page 7 of the PDF called “Bounds of Crossing Numbers.”
Two stand-bys of open learning for math show up at the top of a Google search for “geometry circles.’” One is the colorful Cool Math that been nurtured for a decade, with some advertising support. The other is a Geometry Circles from Math for Morons Like Us, created by the ThinkQuest team in 1998. For more circle investigations, go to University of Birmingham Lecturer Chris Sangwin’s geoGebra page.
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