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Finding the center of a circle with any right angled object

This is the step-by-step, printable version. If you PRINT this page, any ads will not be printed.

See also the animated version.

After doing this Your work should look like this

We start with a given circle.

Geometry construction with compass and straightedge or ruler or ruler
1.  Place the right-angle corner of any object at any point on the circle. Any point will do. Geometry construction with compass and straightedge or ruler or ruler
2.  Make a mark where the two sides of the right-angle cross the circle. Geometry construction with compass and straightedge or ruler or ruler
3.  Draw a line between these two marks. Because of Thales Theorem, this is a diameter of the circle. Geometry construction with compass and straightedge or ruler or ruler
4.  Place the right-angle corner of the object at any other point on the circle. Any point will do, but for greatest accuracy, make it about a quarter the way round the circle from the first point. Geometry construction with compass and straightedge or ruler or ruler
5.  Make a mark where the two sides of the right-angle cross the circle. Geometry construction with compass and straightedge or ruler or ruler
6.  Connect these two points with a straight line. This is the second diameter. Geometry construction with compass and straightedge or ruler or ruler
7.  Done. The point where the two diameters intersect is the center of the circle. Geometry construction with compass and straightedge or ruler or ruler

Other constructions pages on this site

Lines

Angles

Triangles

Right triangles

Triangle Centers

Circles, Arcs and Ellipses

Polygons

Non-Euclidean constructions