Angles at the Centre
- Equal arcs imply the angles at the centre equal.
Condition:
Revision Note - Math - Measures, Shape and Space - Properties of Circle
Angles at the Circumference
- The angle at centre is twice the corresponding angle at circ
Cyclic Quadrilateral
- A pair of opposite angles of cyclic quadrilateral are suppl
Tangents to a Circle
- If $PQ$ is a tangent to the circle at $T$, then $OT$ is perpend