Does that teacher know who he is? Those who know say Ha 10

Drawing a diagram, it is not difficult to find that on the circular runway, when one person is caught up for the first time, the distance difference between the two is the length of the circular runway.

Xiao Ming ran a total of 120 3=360 meters; Mom runs a total of 120 2 = 240 meters.

Therefore, the length of the trail is 360-240=120 meters.

The word "cup" originates from the meaning of "抔", which means holding hands together. The earliest cups were oval-shaped, with ears on both sides, also known as ear cups, and were held in both hands to drink wine. Some of the bronze goblets that were drunk in the Shang and Zhou dynasties had handles, and the lacquer ear cups of the Han Dynasty had ears, which was also equivalent to the function of the handle.

The ear cup is filled with wine, and it can also float on the water, but the ceramics are not good, the bronze is not good, and the wooden tire lacquerware must be used, so the word "cup" is from "wood".

During the Han and Tang dynasties, lacquerware was replaced by porcelain, and porcelain cups were no longer made oval in ear cups, but round. This is because porcelain is drawn into shape on a wheeled cart, and it is convenient to make a circle. Tea began in the Han Dynasty, flourished in the Tang Dynasty, and the world drank tea with porcelain cups, and since then tea and porcelain have formed an indissoluble bond. 

Does the teacher know whose work it is?

The inscriptions on both sides of the picture on the right are - Southern Crown

The southern crown is an idle medal, and I didn't find out who it was

Quartz pebbles, the main chemical component is silicon dioxide, followed by a small amount of iron oxide and trace amounts of manganese, copper, aluminum, magnesium and other elements and compounds. The reason for its formation is the broken rock, the edges and corners disappear through long-distance transportation, forming a garden-shaped or oval stone, produced in the places of rivers and rivers in various places, there are many varieties, the stone pattern has strips, stripes, spots, corrugations and irregular curved strips, etc., mostly black, yellow, blue-gray, its shape is mostly round and shaped, the surface is fine and smooth, flat and smooth, the stone is solid, most of them are irregular blocks, with wax or glass luster, translucent. It can carve the glass and leave the marks before the scratch, no odor and pure talk, and it is not easy to heat quickly and rubbing.

This is a kind of glowstone, ** there are sold, dozens of them.

Put the side of the cone from the BC, it is a fan. The coincidence of b1 and b2 is point b.

Draw a straight line on the sector to connect B1 and B2 for the shortest path.

Principle: Between two points, the line segment is the shortest.

I can't see it clearly, and there is no detailed title.

What is the answer to the detailed question.