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.
A Right triangle contains a 90 degree angle. This can be any of the three angles that make up the triangle. An Acute triangle has an angle that is greater than 0 degrees and less than 90 degrees. An Obtuse triangle is an triangle that contains an angle that is greater than 90 degrees and less than 180 degrees.