Circle and its Parts

1. Circle and its Parts

2. Objectives
At the end of our lesson, we must be able to:
 Identify and define the different parts of the circle
 Recognize the relationship of the different parts of the circle
 Determine how to name (label) each part of the circle

3. What is a CIRCLE?
A circle is a plane curve
consisting of all points
that have the same
distance from a fixed
point

4. Title and Content Layout with SmartArt
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5. Parts of the Circle

6. Center
A circle is a plane curve
consisting of all points that
have the same distance from
a fixed point, called the
CENTER.
In Figure 1 on the right, the
center is called point C. It is
also called Circle C and
labeled as ⨀C.
C
Figure 1

7. Radius
Its measure is half of the
diameter.
C
Figure 1
The radii of a circle are equal
in length.
A line segment that joins any
point on the circle to its center
Example: CM, CP, CS
M P
O
N
Q
R
S

8. Chord
C
Figure 1
It doesn’t necessarily need to
pass the center
A line segment that connects
two points in the circle
Example: MP, NP
M P
O
N
Q
R
S

9. Diameter
C
Figure 1
Its measure is twice the
radius.
A chord that passes through
the center of the circle
Example: MO, SP
M P
O
N
Q
R
S

10. Secant Line
C
Figure 1
Any line that contains the
chord of a circle
Example: MP, SQ
M P
O
N
Q
R
S

11. Tangent Line
C
Figure 1
Any line that intersects at
exactly one point on the circle
Example: K and point M is
the point of tangency
M P
O
N
Q
R
S
It is always perpendicular to
the radius of a circle to the
point of tangency
K
Point of tangency is the point
at which a line intersects a
circle