More than 4000 years ago the Egyptians used ropes knotted in lengths with the ratios 3 to 4 to 5 to form the sides of a triangle in order to determine a right angle. Buildings, and probably the pyramids, were thus erected with the use of elementary, practical trigonometry. Carpenters use this same trick today.
KeywordsRadian Measure Harvest Rate Extinction Time Difference Quotient Degree Measure
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