Pi refers to the ratio of the circumference to the diameter of a circle, which is usually expressed by the Greek letter π. The pinyin of pi is yuá n zh not u l ǜ pa ǜ. This is an irrational number, that is, infinite acyclic decimal, and its value is about 3. 14 159265723846. Pi is an important constant in mathematics and physics, which is widely used to calculate the area, circumference and volume of a circle and the geometric properties of various shapes such as spheres and ellipsoids.

In ancient China, people began to study the related properties and applications of pi. Zu Chongzhi, a mathematician in the Southern and Northern Dynasties, first made Pi accurate to 7 decimal places in the 5th century, which was thousands of years ahead of the world. In the primary school mathematics curriculum in China, the basic knowledge of pi is usually taught, such as the approximate value of π, the formula for calculating the circumference and area of a circle, etc.

Pi is still a very important constant in modern mathematics and physics. It is not only widely used to solve various geometric problems, but also involves many other mathematical fields, such as trigonometric function, series theory, complex variable function and so on.

Application fields of pi;

1, mathematics field:

In the calculation of the geometric properties of a circle, pi is the basic constant for calculating the geometric properties of a circle, such as its perimeter, area and volume. Trigonometric function and series theory, pi plays an important role in trigonometric function and series theory, which can represent many important mathematical functions and order values. Complex number operation, π plays a key role in complex number operation, which together with imaginary unit I forms the basis of complex number.

2, the field of physics:

Electromagnetism, pi has a wide range of applications in electromagnetism, such as calculating various physical quantities in electric and magnetic fields. Optics and pi are also related to optics. For example, calculating the interference and diffraction phenomena of light requires pi. In mechanics and astronomy, pi is also essential when calculating physical quantities such as the trajectory of planets, the inertia and energy of objects.

3. Engineering field:

In mechanical design, pi is used to calculate the size and strength of mechanical parts such as gears, bearings and springs. In aerospace engineering, pi is used to calculate the aerodynamic performance and flight trajectory of aircraft.