When a tangent is drawn to a circle, it makes a right angle with the radius at the point of contact
When an angle is drawn from the ends of an arc to the centre of a circle, it is twice the size of an angle drawn from the ends of the same arc to any point on the opposite circumference of the circle.
When the arc forms a semi-circle, any angle on the circumference is a right angle
7. cyc quad, opp angles add up to 180
When a tangent is drawn to a circle, it makes a right angle with the radius at the point of contact
On a cyclic quad, opposite angles are supplementry
When an angle is drawn from the ends of an arc to the centre of a circle, it is twice the size of an angle drawn from the ends of the same arc to any point on the opposite circumference of the circle.
8. angles on same arc =
Angles extending to the circumference from the same arc are equal
the angle between a chord and a tangent equals the angle in the opposite segment
Any triangle where two of the sides are radii of the same circle must be isosceles.
