law of tangents


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law of tangents

[′lȯ əv ′tan·jəns]
(mathematics)
Given a triangle with angles A, B, and C and sides a, b, c opposite these angles respectively: (a-b)/(a + b) = [tan ½(A-B)]/[tan ½(A + B)].
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(iii) The law of tangents gives the relationship between the sides and tangents of the angles of a triangle:
Trigonometrical identities, Pythagorean identities, and laws for obtaining solutions to triangles (i.e., law of sines, law of cosines, and law of tangents) have been derived.