## Exercise 15

**Q1) Which of the following are simple closed figures?**

Soln:

- It is a simple closed figure because it does not intersect itself.
- It is a simple closed figure because it does not intersect itself.
- It is not a simple closed figure because it intersects itself.
- It is a simple closed figure because it does not intersect itself.
- It is not a simple closed figure because it intersects itself.
- It is a simple closed figure because it does not intersect itself.

**Q2) Which of the following are polygon?**

Soln:

- It is formed by four line segments and we know that a simple closed figure formed by three or more line segments is called a polygon. So it is a polygon named quadrilateral.
- It is formed by three line segments and we know that a simple closed figure formed by three or more line segments is called a polygon. So it is a polygon named triangle.
- It is formed by twelve line segments and we know that a simple closed figure formed by three or more line segments is called a polygon. So it is a polygon
- It is not a polygon because it contains curves.

**Q3) Fill in the blanks**

**(i) A polygon is a simple closed figure formed by more than _____ line segments.**

**(ii) A polygon formed by three line segments is called _____**

**(iii) A polygon formed by four line segments is called a _______**

**(iv) A triangle has ____ sides and _____ angles.**

**(v) A quadrilateral has ____ sides and ____ angles.**

**(vi) A figure which ends at the starting point is called a _______**

Soln:

(i) A polygon is a simple closed figure formed by more than two line segments.

(ii) A polygon formed by three line segments is called triangle.

(iii) A polygon formed by four line segments is called a quadrilateral.

(iv) A triangle has three sides and three angles.

(v) A quadrilateral has four sides and four angles.

(vi) A figure which ends at the starting point is called a closed figure.