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Одна вершина правильного тетраэдра расположена на оси цилиндра, а другие вершины - на боковой поверхности этого цилиндра. Найдите ребро тетраэдра, если радиус основания цилиндра равен R
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Автор:
bellednhu - 5 лет назад
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. Переведите текст в письменной форме:
Subterranean Heat Serves Man
Coal, oil and gas have been man’s main sources of heat from ancient times. At the same time the earth contains inside it practically inexhaustible supply of thermal energy, which without doubt can be used with great profit for economic needs.
Long, long ago magma, surrounding the core of our planet, rose towards the surface but could not burst through the crust and started cooling down gradually. This cooling process has been going on for hundreds of thousands or millions of years. By transferring heat to the rock around it, the magma heats the water in artesian basins and this is how subterranean deposits of hot water originated.
Our country has tremendous quantities of hot subterranean water in the subtropical areas and in the Arctic. The temperature of the water reaches 170 degrees at the depth of up to 3 km. The thermal springs in Russia bring to the surface of the earth an amount of heat equal to that which could be obtained from the combustion of 100-150 million tons of fuel annually.
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The geological and geographical conditions for the presence of thermal water are different but the economic effect of using it is quite great everywhere. Cheap thermal energy will be widely employed in economy in the nearest future, making it possible to utilize such valuable raw materials as coal, oil and gas, mainly in the chemical industry.
Задание 8. Ответьте на вопросы по тексту:
1. Why is it necessary to use subterranean water? 2. Where are the deposits of subterranean water situated? 3. What do people employ hot subterranean water for? 4. What is the economic effect of the heat from thermal springs? 5. When will cheap thermal energy be widely utilized?
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