Triangle Interior and Exterior Angles: Quick Exploration
In the Geometry app below,
1) Use the POLYGON 
tool to construct triangle ABC.
2) Select the ANGLE 
tool. Then click anywhere inside the polygon.
3) Go to the Algebra view (click calculator icon upper left).
4) Calculate the sum of the measures of the interior angles of this triangle. Be sure to add the
Greek letters when doing so! (See the video right below this app to see how to quickly do
this in GeoGebra).
tool to construct triangle ABC.
2) Select the ANGLE tool. Then click anywhere inside the polygon.
3) Go to the Algebra view (click calculator icon upper left).
4) Calculate the sum of the measures of the interior angles of this triangle. Be sure to add the
Greek letters when doing so! (See the video right below this app to see how to quickly do
this in GeoGebra).
Quick (Silent) Demo
Select the MOVE 
tool in the app above. Move any one (or more) of the triangle's vertices around. What can we conclude about the sum of the measures of the interior angles of any triangle?
Here, in this app, we have a triangle with its EXTERIOR ANGLES shown. Calculate the SUM of the measures of these exterior angles here in this app.
Question 2
Select the MOVE tool. Move any one (or more) of the triangle's vertices around.
What can we conclude about the exterior angles of this triangle? Be specific in your response.