Definition of secant in English:

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Pronunciation: /ˈsēˌkant/


1 (abbreviation sec) Mathematics The ratio of the hypotenuse to the shorter side adjacent to an acute angle (in a right-angled triangle); the reciprocal of a cosine.
Example sentences
  • The secant of this angle is 1.61806 which is remarkably close to the golden ratio 1.618034.
  • The secant and cosecant were not used by the early astronomers or surveyors.
  • When you move the cursor over a button on the calculator, a description of its function appears - sine of a number, cosine, secant, etc.
2 Geometry A straight line that cuts a curve in two or more parts.
Example sentences
  • Note that the air mass is approximately equal to the secant of the zenith angle (that angle from directly overhead to a line intersecting the sun).
  • In this projection the meridians are vertical and parallels having increased spacing in proportion to the secant of the latitude.
  • Direct irradiance was attenuated as described by Beer's law, with the optical path length increasing approximately as the secant of the solar zenith angle.


Late 16th century: from French sécante, based on Latin secare 'to cut'.

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