Resources using Dynamic Geometry
Dynamic Geometry programs are multipurpose software tools for
the mathematics classroom.
The files provided on this site can quite easily be adapted for each of the following software package.
Geometer's Sketchpad Program
Cabri Geometry Program
GeoGebra
RITEMATHS files for school use
Geometer's Sketchpad
If your school does not have GSP and you are interested in evaluating
the software then follow this link,
http://www.dynamicgeometry.com/
For many ideas for the use of Geometer's Sketchpad, including JAVA
SKETCHPAD, and many prepared files, click 101projectideas
Cabri Geometry
Another truly excellent dynamic geometry product in CABRI geometry.
Cabri is also available for graphics calculators (TI92 and Voyage
200).
http://wwwcabri.imag.fr/cabri/indexe.html
http://education.ti.com/us/product/software/cabri/features/features.html
GeoGebra
GeoGebra is a free and multiplatform dynamic mathematics software for schools that joins geometry, algebra and calculus. It received several international awards including the European and German educational software awards.
A quick search will link you to a range of tutorials and examples.
www.geogebra.org/
RITEMATHS Files
The resources below use Geometer's Sketchpad, although they can
also be written in other packages such as Cabri Geometry. Resources files will be regularly added to this collection.
Trigonometry
A file to assist students to see how errors in an angle affect distances calculated.
A file to assist students to see how errors in a distance affect distances calculated. 
Land Division (zipped gsp)
This real problem, sent in by a farmer, can use ideas of area, similar figures, geometry, trigonometry and quadratic functions. The dynamic geometry file illustrates the problem and facilitates exploration. 
Ladder Overhang (zipped gsp) : A ladder leans against the wall of a house and overhangs the roof. When is the overhang the greatest?
For calculus students.

River Bank Area (quadratic function with a maximisation problem)

Shot on Goal (zipped gsp) : Year 10 trigonometry problem with numerical or visual optimisation.

Surd Delights : Four activities for exploring surds making use of dynamic geometry.

