Centre of a circle

Marks the centre of a circle. Ruler and compass only.

All parts

Part 1 of 4: Mark three points on the circleStep 1 of 1Pencil

Any three points on a circle fix its centre. Mark any three points on c1, well apart. Call them X, Y and Z.

Keys: left and right arrows step, Space plays or pauses, Escape goes back to all constructions.