GEOMETRY
Chapter:Circle Terminology
1) Radius
A
• The segment joining
the center of a circle to
a point on the circle.
O
• Example: OA
2) Diameter
• A chord that passes
through the center of a
circle.
A
O
• Example: AB
B
3) Chord
• A segment joining two
points on a circle
B
• Example 01: AB
A
C
B
• Example 02: AB
C
A
4) Secant
A
• A line that intersects
the circle at exactly
two points.
C
O
• Example 01: AB
D
B
A
C
• Example 02: AB
O
D
B
5)Tangent
B
C
• A line that intersects a
circle at exactly one
point.
A
• Example: AB
6) Central Angle
A
• An angle whose vertex
is at the center of a
circle.
B
• Example: Angle ABC
C
7)Inscribed Angle
B
A
C
• An angle whose vertex
is on a circle and
whose sides are
determined by two
chords.
• Example: Angle ABC
8) Arc
• A figure consisting of
two points on a circle
and all the points on
the circle needed to
connect them by a
single path.
• Example: arc AB
B
A
.
O
The length of the circle or the distance
around it is called circumference of the
circle.
Relation between radius and diameter
RADIUS = DIAMETER
2
A
OB = AB
2
.
O
B
Ex : If diameter of the circle is 10 cm then find
its radius?
Sol. Radius =diameter / 2
radius=10 cm/ 2
radius =5 cm
A
.
O
Diameter = 10cm
B
Ex: If radius of the circle is 6 cm,then find the
diameter of the circle?
Sol. Diameter = 2 × Radius
Diameter = 2 × 6cm
Diameter = 12 cm
A
Radius = 6cm
.
O
RELATION BETWEEN CIRCUMFERENCE AND
DIAMETER
CIRCUMFERENCE = 𝜋 × DIAMETER
.
DIAMETER
O
A
B
Ex. Find the circumference of the circle whose diameter is
10cm.
Sol. Circumference = 𝜋 × diameter
Circumference = 𝜋 × 10 cm
Circumference = 10 𝜋 cm
.
O
A
DIAMETER=10 CM
B