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.
For example, if we have a Square and we have to rotate it 90 degrees, every time we get the same square. We can find this, 90 degrees by dividing 360 degrees by 4 because 4 sides are present in a square. And we can say that, the rotational symmetry of a square is at every 90 degrees. In a pentagon 5 sides are present so the rotational symmetry is 360 / 5 = 72 degrees. In a Hexagon 6 sides are present so the has rotational symmetry is 360 / 6 = 60 degrees. In a heptagon 7 sides are present so it has rotational symmetry as 360/7 = 51.4 degrees. In an octagon 8 sides are present and it has rotational symmetry as 360/8 = 45 degrees. This is all about rotational symmetry of different polygons.