Negative examples

Positive examples

TriangleRevolution of planet

Hexagon Fan

Negative Positive

SquareRotation of planet

Kite Tyre

CIRCLE : Properties , arcs and points

Std:VII

.O

S P

Q

The Centre of the circle is O.

The radius(r) of the circle is SO.

The diameter (d) of the circle is

PQ

PQ=2 x OP

Properties of the radius &

diameter

Properties of radius:

A

B

C D

E

F G

H

B

.

O

AO=OB=OC=OD=OE=OF=OG=OH=-------------

All the radii of a circle are equal in length.

They are CONGRUENT to each other

A circle has innumerable radii.

Properties of a diameter:

PQ=MN=XY=ST

All the diameters of a circle are equal in length.

All are CONGRUENT to each other

A circle has innumerablediameters.

P

Q

S

T

X

Y

M N

The measure of the diameter of any circle is twice the

length of its radius.

AB=2 x OA

• (if OA=4cm therefore AB=8cm)

AB=2 x OB

A BO

C

Chords of a circle

MN is a chord

• The line segment joining any two points on a circle is called

a chord.

PQ is the longest chord.

• The diameter is the longest chord

A circle has innumerable chords.

MN

P

Q

OS

.

O

Arcs of a circle

.

O

A

B

X

A & B are 2 points on the circle.

The 2 points divide the circle into 2 parts.

Each part is called an arc of the circle.

AXB is an arc.

The interior & exterior of the circle

R.

.S

.W

.F

.K

.M

.N

.Y

.

T

.P

.Q

Points- K,R,S,P,M are inside the circle.

The points which are inside the circle are known as interior points.

Points-W,T,Q,F,N,Y are outside the circle.

The points which are outside the circle are known as exterior points.

There are innumerable points in the interior of the circle, on the circle and in the exterior of the circle.

PARTS OF THE CIRCLE

Radii

diameters

Chords

ARCS

InteriorPOINTS

ExteriorPOINTS

Questions:

Q• Name the centre of the circle.

Q• Name the radii.

Q

• Name the diameters.

Q

• Name the chords.

• Which is the longest chord in the circle?

.O

A

B

C

D

E

F

G

Q• Name the centre of the circle.

Q

• Which points are known as interior points?

• Name the interior points.

Q

• Why is point F known as exterior of the circle?

Q• Name the arcs of the circle.

.D

.J

.

L

.I

.F

M

N

O.K

.S

.T