# circle theorems

sheet of maths circle theorems

- Created by: sophie
- Created on: 19-04-11 11:24

First 106 words of the document:

Circle Theorems

1 Angle in the semi circle is always 90o

2 The radius and a tangent always meet at 90o

3 Angles in the same segment are equal, e.g. ABC=ADC

4 The angle at the centre is twice the angle

at the circumference, e.g. POQ = 2 x

PRQ

5 Opposite angles of a cyclic quadrilateral add up to 180o

i.e. x + y = 1800 & a + b = 1800

6 The lengths of 2 tangent

from a point are equal. RS=RT

7 The angle between a

tangent and a chord is equal to

the angle in the alternate

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