# angles in a triangle (up and down)

By moving point A, how can you make angle A smaller? What will happen to the other two angles then?
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.)
You may also hide all angles during this exploration and estimation.

This is a task in a collection about angles of triangle.

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