By moving point A, how can you make angle A smaller? What will happen to the other two angles then?[br][br]When using the arrow keys in the keyboard (click A and press the keys), you may restrict the movement of A in 4 directions. In particular, you can keep pressing a key to move A upwards, even when it goes outside the window. How will the size of angle A change? Can you estimate its size even when the vertex A is hidden above the viewing window? (Use the check box the hide or show its measurement when trying this estimation.) [br][br]You may also hide all angles during this exploration and estimation.

This is a task in a collection about [url=https://ggbm.at/nh3y2vQf]angles of triangle[/url].