1
The angle subtended by the arc/ chord at the centre is twice the angle subtended by the same arc at any point of the circumference
2
Angle in a semicircle measures 90 degrees
3
Angles in a same segment are equal
4
Opposite angles in a cyclic quadrilateral add up to 180 degrees.
5
The tangent to a circle is perpendicular to the line drawn from radius at any point of the circumference
6
Tangents drawn from an external point will be of the same length
7
The line that joins the external point and the centre of the circle bisects the angle between the tangents
8
The angle between a tangent and a chord is equal to the angle in the alternate segment.