Redesigned, but original idea from http://tube.geogebra.org/material/show/id/157886 by Priyank.
(Total 1 hour's work for record)
Right angle emphasised correctly.
Added construction protocol, text comments and colours for explanation of steps.
Updated version with tracing of perpendicular bisector at
https://www.geogebra.org/material/show/id/rSsUe7YM
