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.
There are two main types of set square. One has an angle of 45 degrees and the other 30/60 degree angles. PDF FILE-CLICK HERE FOR PRINTABLE EXERCISE CLICK HERE FOR FLASH ANIMATION OF SET SQUARES The 45 degree set square also has a 90 degree angle. This can be used for drawing vertical lines. The 30/60 degree set square also has a 90 degree angle. This set square can be used to draw 30, 60 or 90 degrees angles.