China's ancient knowledge about circles.

In ancient China, the circle was a very important research object. In mathematics, astronomy, philosophy and other fields, the circle has played an important role.

First, the definition and nature of the circle

In ancient China, the definition of a circle was mainly based on its image and characteristics. A circle is a figure formed by the rotation of a straight line (or curve) around a fixed point. The center of the circle is the center point of the circle, and the radius is the line segment connecting the center of the circle with any point on the circumference.

A circle has some basic properties, such as symmetry (taking the center of the circle as the axis of symmetry) and uniformity (all parts of the circle have the same shape and size).

Second, the calculation of the circle

In ancient China, pi was an important mathematical constant. Pi is used to calculate the circumference, area and volume of a circle. Ancient mathematicians in China used various methods to calculate pi, such as Liu Hui's "circle cutting method" and Zu Chongzhi's "composition method". Pi is widely used in the fields of engineering and architecture.

Third, the application of circle in astronomy

In ancient China, circles also played an important role in astronomy. The trajectories of the sun, the moon and the stars are considered to be circular motions with the sky as the background. Circle is also used to describe the size and shape of celestial bodies, such as the diameter of celestial sphere and the equatorial radius of celestial bodies.

Fourthly, the application of circle in philosophy.

In China's ancient philosophy, the circle was also endowed with important symbolic significance. It is regarded as a symbol of perfection, harmony and eternity, and also a model of the universe. Taoist thought holds that human beings should follow the laws of nature, and circular motion is considered as an ideal form of motion.

Symbolic meaning of circle

1, perfect

In China culture, the circle is usually regarded as a symbol of perfection and perfection. This is because it has no beginning or end, no flaws or cracks, representing integrity and unity. In China's traditional art design, the circle is often used to express perfection and perfection.

2. Harmony and unity

In China culture, the circle is also a symbol of harmony and unity. In China's traditional philosophy, "harmony" is the highest principle and goal of the development of things. The appearance of China's ancient pi further embodies this concept. The circle has no beginning and end in space, no conflict and contradiction, and represents harmony and unity.

3. Auspicious and prosperous

In China culture, the circle also has the symbolic meaning of auspiciousness and prosperity. In the traditional customs of China, circular patterns, objects or behaviors are often regarded as auspicious symbols, such as red envelopes and moon cakes. This is because the circle represents auspiciousness and prosperity.