9(a)Circle TheoremsEasy2 marksA, B and C are points on the circumference of the circle, centre O.DAE is a tangent to the circle at A. DE is parallel to BC. BOE is a straight line.Write down the two geometrical reasons to explain why angle AOE=55∘.Two answers required.AAngles on a straight line add up to 180∘BThe angle in a semicircle is 90∘CThe angle between a tangent and a radius is 90∘DAlternate angles are equalEThe base angles of an isosceles triangle are equalFCorresponding angles are equalGAngles in a triangle add up to 180∘HOpposite angles of a cyclic quadrilateral add up to 180∘IThe angle at the centre is twice the angle at the circumferenceGrade answerSolutionGrading criteria