Question

Closed figure by straight lines

Answer 1

A polygon is a closed figure on a plane bounded by (straight) line segments as

its sides. Where the two sides of a polygon intersect is called a vertex of the

polygon.

A polygon with three sides is a triangle.

A B

C

We name a triangle by its three vertices. The above is 4ABC. Notice the use of

the little triangle next to the vertices to indicate we are referring to the triangle

instead of the angle.

A polygon with four sides is a quadrilateral.