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Задано точки А(-3;5;-2), В(1;-1;6), точка К — середина відрізка АВ. Знайдіть: а) координати векторів АВ , ВК ; б) довжину вектора АК
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Предмет:
Математика -
Автор:
valentino - 5 лет назад
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Ответы 1
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Применен координатно-векторный метод
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Автор:
jaidynzw6r - 5 лет назад
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Переведите пожалуйста нормально на русский, чтобы все слова были связны.
THE WHEEL, STEAM CARRIAGES AND RAILWAYS
One of mankind’s earliest and greatest inventions was the wheel. Without it there could be no industry, little transportation or communication, only crude farming, no electric power.
Nobody knows when the wheel was invented. There is trace of the wheel during the Stone Age, and it was not know to the American Indians until the White Man came. In the Old World it came into use during the Bronze Age, when horses and oxen were used as work animals. At first all wheels were solid discs.
The problem to be solved was to make the wheels lighter and at the same time keep them strong. At first holes were made in the wheels, and they became somewhat lighter. Then wheels with spokes were made. Finally, the wheel was covered with iron and with rubber.
Light two-wheeled carriages were used widely in the ancient world. As time passed they were made lighter, stronger, and better. Later people joined together a pair of two-wheeled vehicle. At first only kings and queens had the privilege of driving in them.
In the West the first steam carriage was invented in France. The three-wheeled machine had the front wheel driven by a two-cylinder steam engine, and carried two people along the road at a walking pace. It was not a great success, as the boiler did not produce enough steam for keeping the carriage going for more than about 15 minutes.
The steam engine appeared in 1763. It was followed by several improved steam road carriages. Their further development was prevented by railway companies. The rapid spread of railways in the United Kingdom was due largely to George Stephenson, who was an enthusiast as well as a brilliant engineer.
He demonstrated a locomotive that could run eighteen kilometers an hour and carry passengers cheaper than horses carried them. Eleven years later Stephenson was operating a railway between Stockton and Darlington. The steam locomotive was a success.
In Russia the tsar’s government showed little interest in railway transportation. After long debates the government, which did not believe in its own engineers, finally decided to invite foreign engineers to submit (представить) projects for building railways in Russia.
Yet at the very time when foreign engineers were submitting their plans, in the Urals a steam a stem locomotive was actually in use. It had been invented and built by the Cherepanovs, father and son, both skilful mechanics and serfs (крепостные). The first Russian locomotive was, of course, a “baby” compared with the locomotives of today. Under the boiler (котел) there were two cylinders which turned the locomotive’s two driving wheels (there were four wheels in all). At the front there was a smoke stack (труба), while at the back there was a platform for the driver.-
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В равнобедренном треугольнике периметр равен 42 см,а основание 10 см найдите боковые стороны этого треугольника
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