The book was likely finished sometime in late 1987 or early 1988]. II.The collapse of Communism in the Balkans. It is likely that Gorbachevâs ideas for liberalizing East European communist states worked out best in the Balkan states of Bulgaria and Romania.
A polygon is a  closed plane figure made of three or more straight line segments. The term originated from ancient Greek polygonon, which breaks down to polus (many) and gonia (angle). A polygon is a closed plane figure made of three or more straight line segments.
Cartesian Plane. The French mathematician Rene Descartes first introduced the Cartesian plane. The word âCartesianâ comes from the Latin word Cartesium. The idea to explain the Cartesian plane was developed by Rene Descartes and Pierre de Fermat in 1637.