\input zb-basic \input zb-matheduc \iteman{ZMATH 2007a.00354} \itemau{Radi\'c, Mirko} \itemti{On polygons with inscribed and circumscribed circles and on the Poncelet's closure theorem. (O poligonima kojima se mo\v{z}e opisati i upisati kru\v{z}nica i Panceletovu teoremu zatvaranja.)} \itemso{Mat.-Fiz. List 55, No. 219, 135-144 (2004-2005).} \itemab Summary: A bicentric polygon is defined as a polygon which has both inscribed and circumscribed circle. In connection with bicentric polygons it is formulated the Poncelet's closure theorem. For triangles is given one proof of the Poncelet's theorem and some of the relations. \itemrv{~} \itemcc{G44} \itemut{bicentric polygon} \itemli{} \end