Geometry Circle Theorem for IGCSE and O Levels

1. GEOMETRY
ANGLE PROPERTIES OF CIRCLE

2. BASICS OF CIRCLE
 Line from the center of the circle to the circumference is called radius.
 Line from one end of the circumference to the other end and passing from
the center of the circle is called the diameter.
R D

3. Understanding Segment and Sector

4. Property 1: Perpendicular Bisector of a
Chord
 Perpendicular bisector of a chord of a circle passes through the center of the
circle.

5. Property 2: Equal Chords
 Chords that are equidistant from the center of the circle are equal in
length.

6. TANGENT PROPERTIES OF CIRCLE
Property 1: Tangent Perpendicular to
Radius

7. Tangent Properties of Circle
Property 2: Two Tangent Theorem
 Tangents from an external point are equal in length. Line from the center
of the circle to the external point bisects the angle between the two
tangents from the external point.
Tangent Properties of Circle
Property 2: Two Tangent Theorem

8. Tangent Properties of Circle
Property 2: Two Tangent Theorem

9. Angle Properties of A Circle
Property 1: angle at center = 2*angle at circumference

10. Angle Properties of A Circle
Property 2: Right Angle in Semicircle

11. Angle Properties of A Circle
Property 3: Angles in the same segment are equal

12. Angle Properties of A Circle
Property 4: Cyclic Quadrilateral

13. Angle Properties of A Circle
Property 4: Cyclic Quadrilateral

14. Angle Properties of A Circle
Property 5:Alternate Segment
Theorem

15. Angle Properties of Polygons
 Sum of internal angles of a regular shaped polygons can be found from
the formula
 One internal angle of a regular polygon can be found from the formula

16. Internal and External Angles of
Polygons