plane trigonometry
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Related to plane trigonometry: spherical trigonometry
plane trigonometry
[′plān trig·ə′näm·ə·trē] (mathematics)
The study of triangles in the euclidean plane with the use of functions defined by the ratios of sides of right triangles.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.