it under the following license: English In a cyclic quadrilateral, angle A is equal to Γ's exterior angle. Greek Σε ένα εγγεγραμμένο τετράπλευρο η γωνία...
situation where all three actions are not trivial. It is not a “true” quadrilateral: yellow and black sides are bent arcs, not line (i.e. great circle)...
_60-90-60.svg){kind=link}