In this page we practice deciding whether a shape is a polygon or not.
Remember that a polygon must be closed, made of straight line segments, and be two-dimensional.
Example 1
A shape has three straight sides and is closed.
Is it a polygon?
Yes.
It is a triangle, so it is a polygon.
Example 2
A shape is closed but one side is curved.
Is it a polygon?
No.
Not all sides are straight.
Example 3
A shape has five straight sides but has a gap.
Is it a polygon?
No.
The shape is not closed.
Example 4
A star shape is closed and all sides are straight.
Is it a polygon?
Yes.
It is a polygon.
Example 5
A cuboid is a three-dimensional shape.
Is it a polygon?
No.
A polygon must be two-dimensional.
Practice
- More Examples