O is the centre of this circle.
a) What is the size of angle ABC?
b) Which circle theorem below allows you to
find this angle?
A
B
O
C
Not drawn accurately
Angles in the same segment
are equal
The angle between the tangent
and the radius at a point on a
circle is 90°
Opposite angles in a cyclic
quadrilateral add up to 180°
The angle at the circumference
in a semicircle is a right angle
