Question 20390
 How do I find the centre of a circle ? I done this in high school, but that was 25 years ago, and now I just can't remember it.

Use two theorems:

1. The perpendicular bisector of a chord is a diameter.
2. The midpoint of a diameter is the center.

So, draw a chord.  Draw its perpendicular bisector, which is a diameter.  Then find its midpoint.  This is the center.

Edwin
AnlytcPhil@aol.com