Circle Theorems

Rule 1-  angle at the centre is twice the angle at the circumference

Rule 2-   Angles at the circumference are equal

Rule 3-  The angle in a semi-circle is 90c 

Rule 4-  all opposite angles add up to 180c 

Rule 5-  Alternate Segment theorem

Rule 6-  the angle between a tangent and a radius is 90c