1. GEOMETRY
Circle Terminology

2. Component of Geometry Point (dot) Line At least two points given
Angle  If two line intersect in a point
Plane  Something which has area
Space  something which boundary at least by two plane

3. Circle Set of points which have same distance into one permanent point
Same distance = radius = r
Permanent point is central point

4. Radius (or Radii for plural)
The segment joining the center of a circle to a point on the circle.
Example: OA
adopted from

5. Diameter d=2r A chord that passes through the center of a circle.
Example: AB
What is AO?
What is OB?
What is relation between radius and diameter?
Radius
Radius
d=2r

6. Chord
A segment joining two points on a circle
Example: AB

7. Chord A segment joining two points on a circle Example: AB
AB= diameter
So, what is relation between chord and diameter?
Diameter is the longest chord

8. Secant A line that intersects the circle at exactly two points.
Example: AB

9. Secant A line that intersects the circle at exactly two points.
Example: AB

10. Tangent A line that intersects a circle at exactly one point.
Example: AB

11. Central Angle An angle whose vertex is at the center of a circle.
Example: Angle ABC

12. Inscribed Angle
An angle whose vertex is on a circle and whose sides are determined by two chords.
Example: Angle ABC

13. 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
What is the longest arc?
circumference

14. Intercepted Arc
An arc that lies in the interior of an inscribed angle.
Example: arc AC

15. Two Intercepted Arc If angle is inside the circle. Example: arc AC
arc DF

16. Two Intercepted Arc If angle is outside the circle. Example: arc DE
arc DC

17. Apothem The shortest distance between center point and chord
Example: OA A

18. Segment Area which bordered by arc and chord
Shaded area is minor segment
Plain area is major segment O

19. Sector Area which bordered by two radii and an arc
Shaded area is minor sector
Plain area is major sector O

20. Tangents of the circle

21. Requirements:-
Compass
Pencils
Eraser
Scale
Set Square

22. Tangent Chord Secent
If line touches the circle at one point only that is called a tangent
If line connect the two point at the circle that is called a chord
If line intersect the circle at two point that is called secant

23. Formation of tangent D P
Circle
Tangent
Chord C
Secant A B

24. Defination of tangents
APB is called a tangent to the circle
The touching point P is called the point of contact. A P C B

25. When two circles do not touchA B E H P Q G F C D
We construct four tangents AB,CD, EF & GH

26. When two circles touches externally
3rd Tangent
1st Tangent A P B . R . O O’ C Q
2nd Tangent D
We can construct three tangents APB, CQD, PRQ

27. When two circles intersect each other
1st Tangent A B . . O O ! C
2nd Tangent D
We can construct two tangents AB, CD

28. When two circles touches internallyP O O’ B
We can construct only one tangents APB

29. When two concurrent circles
We can not construct any common tangent

30. P is a point out side the circle you can construct two tangents passing through PQ P O R
Tangent PQ = TangentPR

31. Constructing Circumcircle
Steps of Construction C
Construct a Δ ABC
Bisect the side AB
Bisect the side BC o
The two lines meet at O
From O Join B B
Taking OB as radius draw a circumcircle. A

32. Constructing of incircle
Steps of construction
Construct a Δ ABC
Bisect the BAC
Bisect the ABC O
The two lines meet at O
Taking O draw OP AB
Taking OP as radius
Draw a circumcircle A B P