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Introduction to Geometry using the WWW

These sites allow interactive investigation of geometric ideas concerning triangles, angles and parallel lines.

1) http://www.teachnet.ie/tbrophy/concepts.html Preliminary concepts about describing geometric ideas. The Plane, a line, a line segment. Collinear points.

What geometric property of points is being illustrated when the birds fall in flight?

2) http://mathforum.org/~annie/gsp.handouts/investigate/triangle.html Draw triangles. Check how the lengths of sides must match up.

What geometric property of triangles can be deduced from this observation?

3) http://www.cut-the-knot.org/triangle/altitudes.shtml Use the PopUp window for Altitudes, Mediators, Medians, Circumcircle, Incircle.

Could you draw them on your own page?

4) http://www.ies.co.jp/math/products/geo1/applets/kakuhei/kakuhei.html Vertically opposite angles, Correspoding angels, Alternate angles.

What are the three geometric properties of angles which are illustrated here?

5) http://www.mathsnet.net/dynamic/cindy/para_props.html Corresponding and alternate angles. Move the parallel lines and also move the transversals. Can you move them in to a position where the green angles are equal to the yellow angles?

What geometric property is illustrated when the green and yellow angles are equal?

6) http://home.wxs.nl/%7ehklein/jspgenerator/dial.htm Bisect a line segment. Can you move point A to form a mediator?

What are the geometrical properties of a mediator?

7) http://www.math.csusb.edu/faculty/susan/ref_sym1.gsp.html Experiments with mirror reflection axial symmetries.

Can you draw axial symmetries on your own page?

8) http://www.shodor.org/interactivate/activities/angles/ An interactive test on identifying angle types.

9) http://gofree.indigo.ie/~hallinan/Introduction_to_Geometry/Geometry_on_the_Web.htm Overview of ideas required for the Junior Cert. exam. 20 ideas.

10) http://gofree.indigo.ie/~hallinan/Introduction_to_Geometry/Test_Yourself_Quiz.htm Quiz on 20 ideas.

11) http://gofree.indigo.ie/~hallinan/Introduction_to_Geometry/Geometry_Observations_1.doc Pictorial review of ideas (A). Have you met all these ideas which are required for the Junior Cert. exam?

12) http://gofree.indigo.ie/~hallinan/Introduction_to_Geometry/Geometry_Observations_2.doc Pictorial review of ideas (B). Have you met all these ideas which are also required for the Junior Cert. exam?