如图20,在三角形ABC的边BC与边AB上各取一点PQ,使得BQ=BP；在CA上取一点R使AR=AQ；在BC上取一点P'

如图20,在三角形ABC的边BC与边AB上各取一点PQ,使得BQ=BP；在CA上取一点R使AR=AQ；在BC上取一点P'使
CP'=CR,在AB上取一点Q'使BQ'=BP',在AC上取一点R'使AR'=AQ',在BC上取一点P"使
CP"=CR'求证（1）P与P"点重合（2）点P,Q,R,P',Q',R'六点共圆

Great Wall of China, like the Pyramids of Egypt, the Taj Mahal in India and the Hanging Garden of Babylon, is one of the great wonders of the world. While tourists come to China, Great Wall of China, was certainly a place of interest of the essence. Actually, Great Wall of China is one of the most important symbols of Chinese culture, and of course, indication of Chinese civilization
Anyway, Great Wall of China is one of the most famous place for its scenery and historical relics. It is worth to pay a visit to this inconceivable miracle of Chinese culture. And trust me, you will hardly find something this unimaginable like Great Wall of China in the world.

Great Wall of China of those sections is 7.8 meters high and 6.5 meters wide at its base, narrowing to 5.8 meters on the ramparts, wide enough for five horses to gallop abreast. There are ramparts, embrasures, peep-holes and apertures for archers on the top, besides gutters with gargoyles to drain rain-water off the parapet walk. Two-storied watch-towers are built at approximately 400-meters internals. The top stories of the watch-tower were designed for observing enemy movements, while the first was used for storing grain, fodder, military equipment and gunpowder as well as for quartering garrison soldiers. The highest watch-tower at Badaling standing on a hill-top, is reached only after a steep climb, like "climbing a ladder to heaven". The view from the top is rewarding, hoverer. The Wall follows the contour of mountains that rise one behind the other until they finally fade and merge with distant haze.
A signal system formerly existed that served to communicate military information to the dynastic capital. This consisted of beacon towers on Great Wall of China itself and on mountain tops within sight of the Wall. At the approach of enemy troops, smoke signals gave the alarm from the beacon towers in the daytime and bonfire did this at night. Emergency signals could be relayed to the capital from distant places within a few hour long before the invention of anything like modern communications.
Great Wall of China is divided into two sections, the east and west, with Shanxi Province as the dividing line. The west part is a rammed earth construction, about 5.3 meters high on average. In the eastern part, the core of the Wall is rammed earth as well, but the outer shell is reinforced with bricks and rocks. The most imposing and best preserved sections of Great Wall of China are at Badaling and Mutianyu, not far from Beijing and both are open to visitors.
Great Wall of China of China is so Amazing
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Great Wall of China of China

Great Wall of China of China is so Amazing

Great Wall of China of China is so Amazing