Secondly, many properties and theorems of circle play a key role in mathematics. For example, the perimeter and area of a circle can be calculated by a simple formula, which is very helpful to solve various problems related to the circle. In addition, the concepts of tangent, chord and arc of a circle are also the basis for studying other geometric shapes.
In practical application, the essential characteristics of the circle are also of great significance. First of all, the circle is often used in architecture and design because of its good symmetry and aesthetic feeling. For example, roofs, arches and bridges of buildings often adopt circular structures to provide better stability and aesthetics.
Secondly, circles are also widely used in engineering and science. For example, circular pipes can reduce fluid resistance and improve flow efficiency. The design of circular wheels and ball bearings also takes advantage of the circular characteristics to achieve smoother movement and reduce friction.
In addition, the circle also plays an important role in astronomy and geography. The shape of the earth is similar to an ellipsoid, not a perfect sphere, but it still has the characteristics of a circle. This enables us to use the circle to calculate the distance, azimuth and latitude on the earth.
In a word, the essential characteristics of the circle are very important in mathematics and practical application. As one of the simplest geometric shapes, it provides a basis for studying and understanding other more complex geometric shapes. At the same time, the application of circle in the fields of architecture, engineering, science and geography also shows its importance.