All constructions
AB
Try it on the Geometry BoardUses:Parallel through a point

Divide in a ratio

Makes the point that divides a segment in a ratio you type. Ruler and compass only.

All parts
Part 1 of 5: Draw a helper ray from AStep 1 of 2Ruler

You need a second line to step along. Lay the ruler through A at an angle to AB.

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