cotangent, n. (a.) Trig.
(kəʊˈtændʒənt)
[f. co- prefix 4 + tangent. The L. cotangens is used by Gunther Canon Triangulorum, 1620.]
The tangent of the complement of a given angle. (Abbrev. cot.)
| 1635 I. W. Sciographia 47 So is the tangent of R. Z. P. To the cotangent of R. P. Z. 1704 Harris (cited by Johnson). 1706 Phillips (ed. Kersey), Co-tangent is the Tangent of an Arch of a Circle, which is the Complement of another to 90 Degrees. 1831 Brewster Optics xix. 170 The index of refraction is the cotangent of the angle of polarisation. 1852 De Morgan in R. P. Graves Life Sir W. R. Hamilton III. 387 Put cosines in the middle, sines on the flanks, and cotans on the extreme flanks. |
B. adj. cotangent line = cotangent.
| 1652 Stirrup Horometria iv. i. (1659) 107 The side DE..(for distinction) may be called a Tangent line, and the side FF a Co-tangent line. |