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10-98.

Using the definition of polygon from the Math Notes box in this lesson determine whether each of the following figures is or is not a polygon. Justify your decisions for each figure.

  1. An enclosed shape like a parabola with a line connecting the two ends.

    Can polygons have curved lines?

    No, it is not a polygon.

  1. A triangle

    Are polygons made up of straight line segments connected to each other?

  1. Three triangles connected at a vertex.

    Can the sides of polygons intersect?

    No, it is not a polygon.

  1. A figure that goes up, then right, then diagonally down toward the left, then diagonally down toward the right, then left until it meets the starting point enclosing the figure.

    See part (b) for help.

  1. A triangle where two of the lines extend past the same vertex

    Do all the line segments in a polygon have to connect?

    No, it is not a polygon.

  1. An enclosed star.

    Can the vertices of polygons also point inward?

    Yes, this is called a non-convex polygon.

  1. A trapezoid

    See part (b) for help.

  1. Four line segments where two of the lines did not connect.

    See part (e) for help.