Written records of the history of China date from as early as 1500 BC, from the Shang dynasty (c. 1600â1046 BC). Ancient historical texts such as the Records of the Grand Historian (c. 100 BC) and the Bamboo Annals (296 BC) describe a Xia dynasty (c. 2070â1600 BC) before the Shang, but no writing on a durable medium have survived.
A square is a quadrilateral so it has 360 degrees. A square is a quadrilateral so it has 360 degrees.
Regular pentagons have angles measuring 108 degrees. When one pentagon meets two hexagons, the sum of the angles around the vertex is less than 360 degrees. This results in âpositive curvatureâ like. the surface of a ball. Regular heptagons and larger polygons have angles measuring more than 120 degrees.