Visual Proof for Tiling by Equilateral Triangles

(a) Drag the point on the slider to visualize why tiling the plane works with these regular polygons.[br](b) How many polygons meet at each vertex?[br](c) What is the sum of the [color=#1551b5]angles[/color] meeting at the same vertex?[br][br] [b]Equilateral Triangle[/b]

Information: Visual Proof for Tiling by Equilateral Triangles