A drunkard drank in the mountain temple and died drunk in the ravine:

There is a pot of wine in a temple in the mountains. I eat three pots, and the wine is fatal! If you can't kill, you will be happy. If you die, you will scatter your umbrella and abandon the ditch.

The mood of the "dead" father when he learned that his son was "dead";

My poor son died in vain and stayed in the ravine, which is sad enough.

The scene of the "dead" father looking for his son in the ravine;

Last stand, I'm afraid the baby will be frozen for a long time, and I'll think about it for a long time.

Father found his son in the canyon and brought him back to life. The scene of my son getting lost:

I saved my son and turned around in the cave. I shouldn't stay. Neighbors are happy, children are unhappy, and children have loved their father for a long time. Dad, Le Er doesn't understand. Look before you leap! The children realized. Look before you leap, be willing, and your wife will be willing to wait for a long time.

Pi is the ratio of the circumference to the diameter of a circle, which is generally expressed by the Greek letter π and is a universal mathematical constant in mathematics and physics. 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. In the analysis, π can be strictly defined as the smallest positive real number x satisfying sin x = 0.

Pi is expressed by the Greek letter π (pronounced pài), which is a constant (approximately equal to 3. 14 1592654), representing the ratio of circumference to diameter. It is an irrational number, that is, an infinite cycle decimal.

In daily life, pi is usually expressed as 3. 14, which is used for approximate calculation. The fractional part 3. 14 1592654 is enough for general calculation. Even if engineers or physicists want to make more accurate calculations, they only need to take the values to a few hundred decimal places at best.

References:

Pi _ Baidu encyclopedia