a) What is the size of angle x? b) Which of the circle theorems below allows you to work out this angle? ack to task X The circle below is centred at O. Not drawn accurately Q Search Opposite angles in a cyclic quadrilateral add up to 180° The angle at the circumference in a semicircle is a right angle Two tangents that meet at a point are the same length The angle between the tangent and the radius at a point on a circle is 90° The perpendicular line from the centre of a circle to a chord bisects the chord ​