Circumference And Area of Circle Class-9 RS Aggarwal ICSE Maths Goyal Brothers Prakashan Solutions Chapter-18. We provide step by step Solutions of Exercise / lesson-18 Circumference And Area of Circle for ICSE Class-9 RS Aggarwal Mathematics .

Our Solutions contain all type Questions with Exe-18 with Notes on Circumference And Area of Circle to develop skill and confidence. Visit official Website CISCE for detail information about ICSE Board Class-9 Mathematics.

 Board ICSE Publications Goyal brothers Prakshan Subject Maths Class 9th Chapter-18 Circumference And Area of Circle Writer RS Aggrawal Book Name Foundation Topics Solution of Exe-18 with Notes on Circumference And Area of Circle to develop skill and confidence Academic Session 2021-2022

## Circumference And Area of Circle Class-9 RS Aggarwal ICSE Maths Goyal Brothers Prakashan Chapter-18

: Select Topics : –

Notes on Circle

Exe-18 (form Q-1 to 29 )

Exe-18 (form Q-30 to 47 )

### Notes on Circle

#### Circle Definition

A circle is a closed two-dimensional figure in which the set of all the points in the plane is equidistant from a given point called “centre”. Every line that passes through the circle forms the line of reflection symmetry

• Arc – It is basically the connected curve of a circle
• Sector – A region bounded by two radii and an arc.
• Segment- A region bounded by a chord and an arc lying between the chord’s endpoints. It is to be noted that segments do not contain the centre.
• Centre – It is the midpoint of a circle.
• Chord- A line segment whose endpoints lie on the circle
• Diameter- A line segment having both the endpoints on the circle
• Radius- A line segment connecting the centre of a circle to any point on the circle itself.
• Secant- A straight line cutting the circle at two points. It is also called as an extended chord.
• Tangent- A coplanar straight line touching the circle at a single point.

#### Circle Formulas for Area and Circumference

 Circumference (C) The circumference of a circle is defined as the distance around the circle. The word ‘perimeter’ is also sometimes used, although this usually refers to the distance around polygons, figures made up of the straight line segment. A circle circumference formula is given by   C = πd = 2 π r Where, π = 3.1415

 Area (A) Area of a circle is the amount of space occupied by the circle.The circle formula to find the area is given by Area of a circle = πr2

#### Properties of Circles

Here are some basic properties of circles.

• The outer line of a circle is at equidistant from the center.
• The diameter of the circle divides it into two equal parts
• Circles which have equal radii are congruent to each other.
• Circles which are different in size or having different radii are similar.
• The diameter of the circle is the largest chord and is double of the radius.

#### Common Sectors

The Quadrant and Semicircle are two special types of Sector:

Quarter of a circle is called a Quadrant.

Half a circle is called a Semicircle.

#### Lines

A line that “just touches” the circle as it passes by is called a Tangent.

A line that cuts the circle at two points is called a Secant.

A line segment that goes from one point to another on the circle’s circumference is called a Chord.

If it passes through the centre it is called a Diameter.

And a part of the circumference is called an

#### Secant of circle :

A line that intersects a circle at two points then it is called Secant of circle.

### Exe-18 (form Q-1 to 29 )

Circumference And Area of Circle Class-9 RS Aggarwal ICSE Maths Goyal Brothers Prakashan

Page 226-230

#### Question 1:

A sheet is 11 cm long and 2 cm wide, Circular pieces ……………………… that can be prepared.

#### Question 2:

Find the circumference and area of a circle of radius 17.5 cm.

#### Question 3:

Find the circumference and area of a circle of radius 5 cm.

……………………

…………………….

……………………

#### Question 40:

The wheel of the engine  of a train ………………………. speed of the train.

#### Question 41:

A toothed wheel of diameter 50 cm is attached to a smaller ……………………. one makes 30 revolutions ?

#### Question 42:

A wheel makes 1000 revaluations in covering a distance of 88 km. Find the radius of the wheel.

–: End of Circumference And Area of Circle Class-9 RS Aggarwal  Solutions  :–

Thanks