Center of a Circle

Finding the Center of a Circle

http://www.woodworkingtips.com/etips/2004/11/05/wb

http://www.woodworking.com/article.cfm?article=280

Center Square Tool

http://www.robotroom.com/CircleCenter.html

Mysterious Circles

http://www.ncsec.org/team21/SketchPad.htm

http://www.klrn.org/Teacherline/lesson_plans/mysterious.html