Dynamic Geometry: Orthocenter
The interactive figure above, created with GeoGebra,
shows a triangle ABC with the three altitudes AH1, BH2, and CH3 intersecting at
a point H, called orthocenter.
To explore (show / hide): tap a check box.
To stop/play the animation: tap the icon in the
lower left corner.
To reset the interactive figure to its initial state: tap the icon in the
upper right corner.
To manipulate the interactive figure: tap and drag points or lines.
GeoGebra is free and multi-platform dynamic mathematics software for all levels of education that joins geometry, algebra, tables, graphing, statistics and calculus
application, intended for teachers and students. Many parts of GeoGebra have
been ported to HTML5. It has received several educational software awards in Europe and the USA.