Des's answer to Sarah Tong's Secondary 4 E Maths Singapore question.

done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
Des
Des's answer
9 answers (Tutor Details)
using rule 1) angle at centre is twice angle at circumference and rule 4) opposite angles in a cyclic quadrilateral add up to 180degrees