Question

What is the name of the closed figure, which can be formed with the least number of vertices?

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Answer 1

Any figure (with more than one vertex) which starts and ends in the same point is called a closed figure.

If we have just two vertices, it will be a line segment and not a closed figure.

Since AB is not a closed figure, let us add another point C, which does not lie on the same line as A and B, as shown.

Join the point C with A and B, so that we have our first closed figure, a triangle.