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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