Eighth circle theorem: 'Perpendicular bisects the chord'

Perpendicular & chord

A perpendicular line from the centre, O, cuts the chord CD of the circle at point B .

So OB is perpendicular to the chord CD.

Move C or D, and note the connection between lengths CB and DB.

If you want to alter the size of the circle, move O or X.

If you need it, this theorem is set out here

and all the theorems are summarised here

Tim Devereux, Created with GeoGebra