#4.6A
recognise the terms ‘centre’, ‘radius’, ‘chord’, ‘diameter’, ‘circumference’, ‘tangent’, ‘arc’, ‘sector’ and ‘segment’ of a circle
#4.6B
understand chord and tangent properties of circles
Two tangents from a point to a circle are equal in length
Tangents are perpendicular to the radius at the point of contact
The line from the centre of a circle which is perpendicular to a chord bisects the chord (and the converse)
#4.6C
understand and use the internal and external intersecting chord properties
#4.6D
recognise the term ‘cyclic quadrilateral’
#4.6E
understand and use angle properties of the circle including:
(i) angle subtended by an arc at the centre of a circle is twice the angle subtended at any point on the remaining part of the circumference
(ii) angle subtended at the circumference by a diameter is a right angle
(iii) angles in the same segment are equal
(iv) the sum of the opposite angles of a cyclic quadrilateral is180°
(v) the alternate segment theorem
Formal proof of these theorems is not required