The branch of mathematics that deals with the relationships between the sides and the angles of triangles and the calculations based on them, particularly the trigonometric functions.
[New Latin trigōnometria : Greek trigōnon, triangle; see TRIGON + Greek -metriā, -metry.]
trig′o·no·metric (-nə-mĕtrĭk), trig′o·no·metri·cal (-rĭ-kəl) adj.
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