Geometry of Triangles

Trigonometry (from the Greektrigon triangle andmetron measure) is a branch ofmathematics that uses the relationships between the sides and angles of triangles. Theearliest applications of trigonometry were in the fields of navigation, surveying andastronomy. By using trigonometry, it became possible to calculate distances that couldnot be measured directly, such as the distance between the Earth and the Moon, or theheight of a very tall structure.The use of trigonometry was first mentioned on an Egyptian papyrus in about 1800BC.It is clear that people in ancient civilisations were able to measure angles accurately. The pyramids of Egypt and the megaliths of Stonehenge in England were built using a detailed knowledge of angles. Applications of trigonometry are found in physics and virtually all branches of engineering,particularly in the study of periodic phenomena, such as sound vibrations and the flow of alternating current

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