# Copia de GoGeometry Action 166!

Creation of this resource was inspired by a problem posted by Antonio Gutierrez.
The

**LARGE VERTICES**of the**triangle**below can be moved anywhere at any time. The**light green slider**controls the measure of the interior angle with**green vertex**.**Questions to consider:**1) How would you describe the phenomenon you see here in your own words? 2) How can we formally prove this phenomenon holds true for**ANY TRIANGLE**?Download our apps here: