# Frank solutions for Class 9 Maths ICSE chapter 18 - Rectilinear Figures [Latest edition]

## Chapter 18: Rectilinear Figures

Exercise 18.1
Exercise 18.1

### Frank solutions for Class 9 Maths ICSE Chapter 18 Rectilinear Figures Exercise 18.1

Exercise 18.1 | Q 1.1

Find the sum of the interior angles of a polygon of: 7 sides

Exercise 18.1 | Q 1.2

Find the sum of the interior angles of a polygon of: 12 sides

Exercise 18.1 | Q 1.3

Find the sum of the interior angles of a polygon of: 9 sides

Exercise 18.1 | Q 2.1

Find the measure of each interior angle of a regular polygon of: 6 sides

Exercise 18.1 | Q 2.2

Find the measure of each interior angle of a regular polygon of: 10 sides

Exercise 18.1 | Q 2.3

Find the measure of each interior angle of a regular polygon of: 15 sides

Exercise 18.1 | Q 3.1

Find each exterior angle of a regular polygon of: 9 sides

Exercise 18.1 | Q 3.2

Find each exterior angle of a regular polygon of: 15 sides

Exercise 18.1 | Q 3.3

Find each exterior angle of a regular polygon of: 18 sides

Exercise 18.1 | Q 4.1

Find the number of sides in a regular polygon, when each interior angle is: 120°

Exercise 18.1 | Q 4.2

Find the number of sides in a regular polygon, when each interior angle is: 140°

Exercise 18.1 | Q 4.3

Find the number of sides in a regular polygon, when each interior angle is: 135°

Exercise 18.1 | Q 5.1

Find the number of sides in a regular polygon, when each exterior angle is: 20°

Exercise 18.1 | Q 5.2

Find the number of sides in a regular polygon, when each exterior angle is: 60°

Exercise 18.1 | Q 5.3

Find the number of sides in a regular polygon, when each exterior angle is: 72°

Exercise 18.1 | Q 6

The angles of a pentagon are 100°, 96°, 74°, 2x° and 3x°. Find the measures of the two angles 2x° and 3x°.

Exercise 18.1 | Q 7

The three angles of a quadrilateral are 71°, 110°, 95°. Find its fourth angle.

Exercise 18.1 | Q 8

Find the angles of a pentagon which are in the ratio 4: 4: 6: 7: 6.

Exercise 18.1 | Q 9

Find the angles of a quadrilateral whose angles are in the ratio 1: 4: 5: 2.

Exercise 18.1 | Q 10

The angles of a pentagon are x°, (x - 10)°, (x + 20)°, (2x - 44)° and (2x - 70)°. Find the angles.

Exercise 18.1 | Q 11

The angles of a hexagon are (2x + 5)°, (3x - 5)°, (x + 40)°, (2x + 20)°, (2x + 25)° and (2x + 35)°. Find the value of x.

Exercise 18.1 | Q 12

One angle of a hexagon is 140° and the remaining angles are in the ratio 4 : 3 : 4 : 5 : 4. Calculate the measures of the smallest and the largest angles.

Exercise 18.1 | Q 13

One angle of a pentagon is 160° and the rest are all equal angles. Find the measure of the equal angles.

Exercise 18.1 | Q 14

Calculate the measure of each angle of a nonagon.

Exercise 18.1 | Q 15

Calculate the measure of each angle of a regular polygon of 20 sides.

Exercise 18.1 | Q 16.1

Is it possible to have a polygon whose sum of interior angles is 780°?

Exercise 18.1 | Q 16.2

Is it possible to have a polygon whose sum of interior angles is 7 right angles?

Exercise 18.1 | Q 17.1

Is it possible to have a polygon whose each interior angle is 124°?

Exercise 18.1 | Q 17.2

Is it possible to have a polygon whose each interior angle is 105°?

Exercise 18.1 | Q 18

A heptagon has three angles equal to 120°, and the other four angles are equal. Find all the angles.

Exercise 18.1 | Q 19

In a pentagon ABCDE, AB || ED and ∠B = 140°, ∠C = 2x° and ∠D = 3x°. Find ∠C and ∠D

Exercise 18.1 | Q 20

In a polygon, there are 3 right angles and the remaining angles are equal to 165°. Find the number of sides in the polygon.

Exercise 18.1 | Q 21

ABCDE is a pentagon in which AB is parallel to DC and ∠A : ∠E : ∠D = 1 : 2 : 3. Find angle A.

Exercise 18.1 | Q 22

If the difference between an exterior angle of a regular polygon of 'n' sides and an exterior angle of another regular polygon of '(n + 1)' sides is equal to 4°; find the value of 'n'.

Exercise 18.1 | Q 23

The number of sides of two regular polygons are in the ratio 2 : 3 and their interior angles are in the ratio 9 : 10. Find the number of sides of each polygon.

Exercise 18.1 | Q 24

KL, LM and MN are three consecutive sides of a regular polygon. If ∠LKM = 20°, find the interior angle of the polygon and the number of sides of the polygon.

Exercise 18.1 | Q 25

The ratio between the number of sides of two regular polygon is 3 : 4 and the ratio between their interior angles is 2 : 3. Find the number of sides of each polygon.

Exercise 18.1 | Q 26

Find the value of each angle of a heptagon If three of its angles measure 132° each and the remaining four.

Exercise 18.1 | Q 27

Find the value of each angle of an octagon if two of its angles are 148° and 152° and the remaining angles are all equal.

Exercise 18.1 | Q 28

Find the value of each angle of an octagon if four of its angles are equal and the other four are each greater than these by 20°.

Exercise 18.1 | Q 29

The exterior angle of a regular polygon is one-third of its interior angle. Find the number of sides of the polygon.

Exercise 18.1 | Q 30

The number angle of a regular polygon is double the exterior angle. Find the number of sides of the polygon.

Exercise 18.1 | Q 31

The sum of the interior angles of a polygon is 6.5 times the sum of its exterior angles. Find the number of sides of the polygon.

Exercise 18.1 | Q 32

The difference between an exterior angle of (n - 1) sided regular polygon and an exterior angle of (n + 2) sided regular polygon is 6°. Find the value of n.

Exercise 18.1 | Q 33

In a pentagon PQRST, ∠P = 100°, ∠Q = 120° and ∠S = ∠T. The sides PQ and SR, when produced meet at right angle. Find ∠QRS and ∠PTS.

Exercise 18.1 | Q 34

In a hexagon JKLMNO, side JK || ON and ∠K : ∠L : ∠M : ∠N = 6 : 5 : 4 : 3. Find the angle ∠K and ∠M.

Exercise 18.1 | Q 35

In a regular pentagon PQRST, PR = QT intersect at N. Find the angle RQT and QNP.

Exercise 18.1 | Q 36

Each exterior angle of a regular polygon is (1)/"P" times of its interior angle. Find the number of sides in the polygon.

Exercise 18.1 | Q 37

Each interior angle of a regular polygon is 162°. Another regular polygon has number of sides double the first polygon. Find each interior angle of the second polygon.

Exercise 18.1

## Frank solutions for Class 9 Maths ICSE chapter 18 - Rectilinear Figures

Frank solutions for Class 9 Maths ICSE chapter 18 (Rectilinear Figures) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CISCE Class 9 Maths ICSE solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 9 Maths ICSE chapter 18 Rectilinear Figures are Introduction of Rectilinear Figures, Names of Polygons, Concept of Quadrilaterals - Sides, Adjacent Sides, Opposite Sides, Angle, Adjacent Angles and Opposite Angles, Diagonal Properties of Different Kinds of Parallelograms, Property: The Diagonals of a Rectangle Are of Equal Length., Property: The diagonals of a square are perpendicular bisectors of each other., Types of Quadrilaterals, Property: The Opposite Sides of a Parallelogram Are of Equal Length., Property: The Opposite Angles of a Parallelogram Are of Equal Measure., Property: The diagonals of a rhombus are perpendicular bisectors of one another..

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