Properties Of Circles! By Sajan Rai, Giridharan, Shivasuria & Juaquin Hammy

1. 
Circle
Vocabulary
(Definitions)
By: Shiva, Giri, Sajan & Juaquin

2. What is a Circle?
A CIRCLE IS DEFINED AS…
The set of all points in a plane that are
equidistant from a given point called
the center point.

3. Chord – a segment whose endpoints are on the
circle
H
C

4. Diameter – a chord that passes through the center
of the circle.
N
C

5. Radius – a segment that has the center as one endpoint
and a point on the circle as the other endpoint.
(Don’t forget… A diameter is made up of two radii)
P
C

6. Lines that Intersect a Circle
R
 Tangent Line – a line that
intersects the circle at S
exactly one point.
T
C
 That point is called a point
of tangency.

7. Special Cases of Tangent Lines
 A line that is tangent to two circles is
known as a common tangent.
E
A

8. Identify the following by their correct vocabulary
name
D C
CD -AC - di
chor
A
B
F
AB - radiuspo
⋅F - E

9. 
O

10. Major Arc
AB
A
Major sector
O
Minor
sector
Minor
Arc AB
B

11. diameter
chord
Centre
tangent
Tangent is perpendicular to the diameter

12. •If AC = BC
•then ∠OCA =∠OCB = 90°
•OA = OB
O
∀∠OAC =∠OBC
A C B
∀∆OAB is an isosceles
triangle
C
If AB = CD, then
F
D
OE = OF
O
A
E
B

13. •OA = OC
(radius)
A •AB and BC are
the tangents
B ∀∠OAB
O
=∠OCB = 90°
•Hence AB = CB
j ∀∠OBA
C
=∠OBC
∀∠BOA
=∠BOC

14. •The segment
bounded
Q
by the arc APB and
Major
A the chord AB is the
Segment
minor segment of
M O the circle.
Se ino •The segment
gm r
en bounded
P
t by the major arc
B AQB and the chord
AB is the major
Chord AB
segment of the circle.

15. C
∠ACB is subtended
by the minor arc AB
at the point C on the
O
B
circumference.
A

16. O
A
B

17. P
O Q
A
B

18. C
O
A
B

19. C
O
O C
A
A
B
B
∠AOB = 2∠ACB
∠AOB = 2∠ACB

20. C
O
O
A A
B B
C
reflex ∠AOB = 2∠ACB ∠AOB = 2∠ACB

21. C
B
O A

22. C
B
O
D
A

23. B
C
S A T

24. In this circle, TAN is the
tangent of circle A
O
Tangent is _|_ To Radius
T A N