Draw squares ABDE and BCFG on sides AB and BC of a triangle ABC.
Prove the following:

CD and AG are congruent and
perpendicular

CD, AG, and EF are
concurrent in H

EF is bisector of angle GHC.
Click the
red button ()
on the figure to start the animation.
Drag points A, C, and line AC to change
the figure. Press P and click the left mouse button to start the step by step
construction.
Dynamic Geometry or Interactive Geometry Software are computer programs which allow one to create and then manipulate geometric constructions, primarily in plane geometry. One starts construction by putting a few points and using them to define new objects such as lines, circles or other points. After some construction is done, one can move the points one started with and see how the construction changes. You can alter the figure
dynamically in order to test and prove (or disproved)
conjectures and gain mathematical insight that is less
readily available with static drawings by hand.
This page uses the
TracenPoche
dynamic geometry software and requires
Adobe Flash player 7 or higher.
TracenPoche is a project of Sesamath, an association of French
teachers of mathematics.
Instruction to explore the
dynamic figure:

Animation. Click the red
button
to start/stop animation

Manipulate. Drag points A
and C, and line AC to change the figure.

StepbyStep construction.
Press P and click the left mouse
button
on any free area of the figure
above to show the
stepbystep bar and click 'Next
Step' button ()
to start the construction stepbystep:
Hide the stepbystep bar by
using again the combination P +
click left mouse.
