CIRCLES

1

WHAT ARE CIRCLES?The collection of all the points in a plane

which are at a fixed distance from a fixed

point in a plane , is called a CIRCLE.

REMARKs-

1.The line segment joining the

center and any point on the circle

is also called a RADIUS of the

circle.

2.DIAMETER is the longest chord and all

diameters have the same length which is

equal to two times the radius.

3.A piece of a circle between two points is called

an ARC.

REMARKs-4.The length of the complete circle is

called its

CIRCUMFERENCE.

5.The region between a chord and either of

its arcs is called a SEGMENT of circular region

or simply a segment of the circle.

REMARKS-6.There are two major types of

segments , which are the MAJOR

SECTOR and the MINOR SECTOR.

7.The bigger one is

called the MAJOR

SECTOR and the

smaller one is known as

MINOR SECTOR.

RELATION BETWEEN

CIRCUMFERENCE AND

DIAMETERCIRCUMFERENCE = 3 x

DIAMETER(APPROX))

Diameter

CIRCLES-Another prevalent kind of simple closed

curve is a circle. Circles are geometric figures whose points all lie the same distance from a given point, the circle's center. They are not polygons, because they are not made up of segments. Points that lie in the same line, like those in a segment, are never equidistant (an equal distance) from a single point.

FORMULA’S OF CIRCLES-1*Diameter = 2 x radius of circle

2*Area of Circle:area = PI r2

3* Circumference of Circle = PI x diameter = 2 PI x radius

where PI = PI = 3.141592...

4* Length of a Circular Arc: (with central angle theta).

if the angle theta is in degrees, then length = theta x (PI/180) x r

if the angle theta is in radians, then length = r x theta

FORMULA’S OF CIRCLES-5* Area of Circle Sector: (with central angle theta)

if the angle theta is in degrees, then area = (theta/360)x PI r2

if the angle theta is in radians, then area = ((theta/(2PI))x PI r2

THANK YOUNAME- Karan Singh Rawat

CLASS-9TH

SECTION-A

D.C.MODEL SR. SEC. SCHOOL