# GCSE Circle Theorems

GCSE circle theorems; good detailed revision notes with a couple of exam style questions at the end.

## Other slides in this set

### Slide 2

Extracted text:

90°
Angles in a Semi-circle 90°
Angles in semicircle = 90 degrees.
OR
Angles subtended by a diameter = 90
degrees.

### Slide 3

Extracted text:

Angles in the Same Sector
These angles same
These angles same size!
size!
Angles in the same segment are equal.

### Slide 4

Extracted text:

A+C=180
B+D=180
Opposite angles in a Cyclic
Quadrilateral (four-sided shape with its B
corners touching the edge of a circle)
A
C
D

### Slide 5

Extracted text:

Centre Angle/Circumference Angle
A Angle A is half of angle B.
The angle at the
circumference is half of the
angle at the centre.
OR
B The angle at the centre is
double the angle at the
circumference.
Origin (Centre)

### Slide 6

Extracted text:

Alternate Segment Rule
This applies where
Angle A = Angle B
there is a triangle in a
Angle C = Angle D circle and one corner
A is touching a tangent
to the circle.
C
Angles in alternate
segments are
equal.
B D