# NCERT Class 8 Mathematics Solutions: Chapter 3 – Understanding Quadrilaterals Exercise 3.1 Part 5 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question: 5** What is a regular polygon? State the name of a regular polygon of:

(a) 3 sides

(b) 4 sides

(c) 6 sides

**Answer**:

**A regular polygon**: A polygon having all sides of equal length and all angles are equal is known as regular polygon.

**(a) 3 sides**:

Polygon having three sides is called a **Triangle**.

**(b) 4 sides**:

Polygon having four sides is called a **Quadrilateral**.

**(c) 6 sides**

Polygon having six sides is called a **Hexagon**.

**Question: 6** Find the angle measures *x* in the following figures:

(a)

Image

(b)

Image

(c)

Image

(d)

Image

**Answer**:

**(a)** The figure is having 4 sides. Hence, it is a quadrilateral.

Using angle sum property of a quadrilateral,

Image:

**(b)** The figure is having 4 sides. Hence, it is a quadrilateral. Also, one side is perpendicular forming right angle.

Using angle sum property of a quadrilateral,

Image:

(c) The figure is having 5 sides. Hence, it is a pentagon.

Image:

First base interior angle

Second base interior angle

There are 5 sides,

(d) The figure is having 5 equal sides. Hence, it is a regular pentagon. Thus, it՚s all angles are equal.

Image:

Angle sum of a polygon

There are 5 sides,

Hence, each interior angle is