compass and straightedge construction of center of given circle
Given a circle in the Euclidean plane^{}, one can construct its center (http://planetmath.org/Center8) using compass and straightedge as follows:

1.
Draw a chord. Label its endpoints^{} as $A$ and $B$.

2.
Construct the perpendicular bisector^{} of $\overline{AB}$ in order to find the two points $C$ and $D$ where it intersects the circle.

3.
Construct the perpendicular bisector of $\overline{CD}$ to determine the midpoint^{} $O$ of $\overline{CD}$. $O$ is the center of the circle.
A justification for these constructions is supplied in the entry construct the center of a given circle.
If you are interested in seeing the rules for compass and straightedge constructions, click on the provided.
Title  compass and straightedge construction of center of given circle 

Canonical name  CompassAndStraightedgeConstructionOfCenterOfGivenCircle 
Date of creation  20130322 17:13:44 
Last modified on  20130322 17:13:44 
Owner  Wkbj79 (1863) 
Last modified by  Wkbj79 (1863) 
Numerical id  10 
Author  Wkbj79 (1863) 
Entry type  Algorithm 
Classification  msc 51M15 
Classification  msc 5100 
Related topic  ConstructTheCenterOfAGivenCircle 