Question 4: Consider the given figure and answer the question:
Is it a curve?
Closed curves are the shapes that are closed by line-segments or by a curved line.
e.g. A circle is an example of such a closed curve.
The shape which is not closed by line-segments or a curve is called an open curve, e.g. figure 1.
Figure 2 doesn't have endpoints and it completely encloses an area.
Hence, it is a curve.