Geometry 4-2b GeoGebra Primer: SAS: Dynamic Proof

By Matthew Richardson

Last updated over 3 years ago

5 questions

The SAS Triangle Congruence Theorem states that if 2 sides and their included angle of one triangle are congruent to 2 sides and their included angle of another triangle, then those triangles are congruent. The applet below uses transformational geometry to dynamically prove this very theorem.  

Interact with this applet below for a few minutes, then answer the questions that follow.   As you do, feel free to move the BIG WHITE POINTS anywhere you'd like on the screen!   

What does the top-most slider in the top right corner control?

What does the middle slider in the top right corner control?

What does the bottom slider in the top right corner control?

What does the slider in the bottom left corner control?

How does this applet demonstrate the SAS Triangle Congruence Theorem, which states that if 2 sides and their included angle of one triangle are congruent to 2 sides and their included angle of another triangle, then those triangles are congruent.