Cyclic quadrilateral Post author By Rik D. Tangerman Post date December 7, 2020 No Comments on Cyclic quadrilateral A quadrilateral whose vertices all lie on a single circle. In it, opposite angles add up to 180°. ← Intersecting chords theorem → Inscribed angle theorem Leave a Reply Cancel replyYour email address will not be published. Required fields are marked *Comment * Name * Email * Website Save my name, email, and website in this browser for the next time I comment. Δ Optionally add an image (JPEG only)