How to Find the Centre of a Circle 2b3a

The POSH way o6517

1p332h

Draw a chord anywhere across your circle (marked in yellow on the picture) Construct the perpendicular bisector (marked in blue on the picture). Draw another chord and do the same thing. Where the bisectors cross will be the centre. 2k3u4t

The USING A BOOK way 4h4o1i

1/ Get a circle		2/ Get a book that's at least as big as the circle. (If you haven't got a book you can use a rectanglular piece of paper).		3/ Put one corner of the book on the edge of the circle (See "C") Mark where the two edges of the book cross the circle (See "X" and "X")
4/ Remove the book and the marks with a straight line. This will be a diameter of the circle		5/ Do it again to get another diameter.		6/ Where the diameters cross is the centre.

This works thanks to the fact that the angle in a semi-circle is always a right angle. There's more of this stuff in Murderous Maths Main Index Page 710o