Angle and circle characterizations of tangential quadrilaterals - Martin Josefsson We prove five necessary and sufficient conditions for a convex quadrilateral to have an incircle that concerns angles or circles. ✪ ✪ ✪ ✪ ✪ Hidden Content: **Hidden Content: Content of this hidden block can only be seen by members of (usergroups: V.I.P Downloader).** Theo LTTK Education