Directions:

1. Move points A, B and C to change the triangle’s shape and size.


2. Next, move the green point on the slider completely to the right. What is the sum of the three angles?


3. Repeat steps (1) and (2). What do you observe about the sum of the angles?


4. What mathematical reason can be used to justify the two green-shaded angles are congruent?;
   the two blue-shaded angles are congruent?;
   and the two brown-shaded angles are congruent?

Sorry, the GeoGebra Applet could not be started. Please install Java 1.4 (or later) to use this page.
Applet created by Steven Lapinski

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Directions:

1. Move the vertices of ∆ABC around.


2. Notice that the angles change when you move the vertices.


3. Pull the red slider to watch the animation.


4. What mathematical concept are you supposed to learn from this applet?

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)
Applet created by Duane Habecker, 4/12/07