Apollonius is the first (and so far the only) Interactive Geometry Software (IGS) for the iPhone and iPod Touch. It allows you to make geometric constructions (such as those made using a compass and straightedge/ruler) and move their parts smoothly using the device's touchscreen.
Apollonius was inspired by similar software for personal computers, such as Cabri and The Geometer's Sketchpad.
An example of a simple construction that can be made with Apollonius is a triangle with its medians, heights, and angle bisectors. Moving the vertices of the triangle will then simultaneously move the medians, heights and angle bisectors accordingly.
Apollonius remembers your last construction when the program is closed. It also allows you to ZOOM and SCROLL your construction, providing a very large virtual screen.
New versions will start appearing soon with great new features, so make sure to visit this page once in a while. Updating to a new version is FREE once you have bought the app!
About IGSs: Interactive geometry environments are powerful tools in the development of problems and conjectures in planar geometry. They have also proven to be very useful as educational tools.