Orthocentre

Marks the orthocentre: where the altitudes of a triangle meet. Ruler and compass only.

All parts

Part 1 of 3: Perpendicular from A to BCStep 1 of 12Compass

Draw the line from A that meets BC at a right angle (extend BC if you need to). Put the point of your compass on A.

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