Zu Chongzhi, an ancient mathematician in China, approximated the circumference of a circle with the circumference inscribed by a regular polygon, thus obtaining the value of π accurate to the seventh decimal place.
π = perimeter/diameter ≈ inscribed regular polygon/diameter. When the side length of a regular polygon is longer, its circumference is closer to a circle. The π value calculated by Zu Chongzhi has been very accurate in most practical applications.
Pi is the ratio of the circumference to the diameter of a circle, which is generally expressed by the Greek letter π. π is also equal to the ratio of the area of a circle to the square of its radius. Accurate calculation of geometric shapes such as circle perimeter, circle area and sphere volume is the key value. ?
Pi in Greek letters? π (pronounced pài) is a constant (approximately equal to 3. 14 1592654), which is the ratio of circumference to diameter. It is an irrational number, that is, an infinite cycle decimal.
References:
Baidu encyclopedia -pi