Interactive resource
Perpendicular chord theorem
Geometry. A diameter perpendicular to a chord bisects the chord (and its arcs). Free interactive GeoGebra resource — adjust parameters in the browser.
Overview
A diameter perpendicular to a chord bisects the chord (and its arcs).
Explanation
A diameter perpendicular to a chord bisects the chord and the arcs it subtends.
Corollaries: the perpendicular from the center to a chord bisects it; the perpendicular bisector of a chord passes through the center.
Often drop a perpendicular radius to a chord when computing lengths.
How to use
Drag chord endpoints A, B; foot M stays the midpoint and OM ⊥ AB.