Angles in Circles Angles on the circumference Angles from a diameter Angles at the centre & the circumference Cyclic quadrilaterals Tangents
Angles on the circumference Angles on the circumference from opposite ends of a chord are the same
Angles from a diameter Angles on the circumference from opposite ends of a diameter are 90°
Angles at the centre & the circumference Angles on the circumference from opposite ends of a chord are half of the angle at the centre (from the same chord)
Cyclic quadrilaterals Opposite angles of a quadrilateral on the circumference total 180°
Tangents The angle between a tangent and a radius (where the tangent touches the circle) is 90°