NCERT Solutions for Class 8 Chapter 3 Understanding Quadrilaterals -Free PDF Download

Free PDF download of NCERT Solutions Maths Class 8 Solutions Chapter 3 – Understanding Quadrilaterals solved by Expert Maths Teachers on CoolGyan.Org. All Chapter 3 – Understanding Quadrilaterals Questions with Solutions for NCERT to help you to revise complete Syllabus and Score More marks.

Maths Revision Notes for Class 8

NCERT SOLVED

1. Find  in the following figures:

Ans. (a) Here, 

[Linear pair]

And  

[Linear pair]

∵∵ Exterior angle  = Sum of opposite interior angles

∴∴ 

(b) Sum of the angles of a pentagon

= 

= 

= 

By linear pairs of angles,

  ……….(i)

  ……….(ii)

  ……….(iii)

  ……….(iv)

   ……….(v)

Adding eq. (i), (ii), (iii), (iv) and (v),

2. Find the measure of each exterior angle of a regular polygon of:

(a) 9 sides

(b) 15 sides

Ans. (i) Sum of angles of a regular polygon = 

= 

Each interior angle = 

Each exterior angle = 

(ii) Sum of exterior angles of a regular polygon = 

Each exterior  angle = 360/15360/15

= 24 degrees

3. How many sides does a regular polygon have, if the measure of an exterior angle is 

Ans. Let number of sides be 

Sum of exterior angles of a regular polygon = 

Number of sides = 

Hence, the regular polygon has 15 sides.

4. How many sides does a regular polygon have if each of its interior angles is 

Ans. Let number of sides be 

Exterior angle = 

Sum of exterior angles of a regular polygon = 

Number of sides = 

Hence, the regular polygon has 24 sides.

5. (a) Is it possible to have a regular polygon with of each exterior angle as 

(b) Can it be an interior angle of a regular polygon? Why?

Ans. (a) No. (Since 22 is not a divisor of )

(b) No, (Because each exterior angle is  which is not a divisor of )

6. (a) What is the minimum interior angle possible for a regular polygon? Why?

(b) What is the maximum exterior angle possible for a regular polygon?

Ans. (a) The equilateral triangle being a regular polygon of 3 sides has the least measure of an

interior angle of 60∘.60∘.

∵∵ Sum of all the angles of a triangle

= 180∘180∘

∴∴ 

(b) By (a), we can observe that the greatest exterior angle is 

.