Brief
 User interacts with construction and notices that the triangle constructed under the given conditions "appears" to be a right triangle. He then uses standard 6th grade geometric facts to "prove" that the angle is in fact 90°. Finally, in a second interactivity the user constructs the triangle.

Preknowledge
 The sum of the angles of a triangle is 180°, the sum of supplementary angles is 180° the angles at the base of an isosceles triangle are congruent (equal size).

Goal
 Understanding triangles, angles and logical conclusions.

Grade
 69 (6th grade, 7th grade, prealgebra, geometry)

Strand
 Measurement and Geometry, Geometry

Standards
 CA 6.MG.2.2, CA Geometry 13.0, ACT PF 2427

Keywords
 triangles, medians, righttriangles, construction, interactivity, geogebra

Comments
 Suitable for 6thgrade on up.

Source
 Linda FahlbergStojanovska (no copyright)

Cost
 Activity and software is free to use

Download
 Zip for offline use: tri_median_right.zip (includes handout, teachers page, 2 ggb interactivities)
Requires freeware GeoGebra for offline use.

Type
 Java Applet so requires free sunJava player
