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.
The more familiar unit of measurement is that of degrees. A circle is divided into 360 equal degrees, so that a right angle is 90Â°. For the time being, weâll only consider angles between 0Â° and 360Â°, but later, in the section on trigonometric functions, weâll consider angles greater than 360Â° and negative angles.