Harmonic conjugate

Makes the harmonic conjugate of a point on the line through two others. Ruler and compass only.

All parts

Part 1 of 7: Pick a point X off the lineStep 1 of 1Pencil

You only need the ruler (and a pencil) for this one. Mark any point off line AB. Call it X.

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