Question

Line || line m || line n. Find angles a, b, c, d, e
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Answer 1

Whether in prehistoric or historic times, people always needed to be near reliable sources of potable water. Settlements developed as early as 4,000 BCE in Iran,[3][4][5][6][7] in Mesopotamia,[8] in the Indus River valley,[9] on the banks of Egypt's Nile River,[10][11] and along China's rivers.[12][13] As farming developed, grain agriculture became more sophisticated and prompted a division of labour to store food between growing seasons. Labour divisions led to the rise of a leisured upper class and the development of cities, which provided the foundation for civilization. The growing complexity of human societies necessitated systems of accounting and writing.