Trigonometric function

In mathematics, the trigonometric functions are a set of functions which relate angles to the sides of a right triangle. There are many trigonometric functions, the 3 most common being sine, cosine, tangent, followed by cotangent, secant and cosecant.^[1][2] The last three are called reciprocal trigonometric functions, because they act as the reciprocals of other functions. Secant and cosecant are rarely used.

Function	Abbreviation	Relation (Radians)
Sine	sin	${\displaystyle \sin \theta =\cos \left({\frac {\pi }{2}}-\theta \right)\,}$
Cosine	cos	${\displaystyle \cos \theta =\sin \left({\frac {\pi }{2}}-\theta \right)\,}$
Tangent	tan (or tg)	${\displaystyle \tan \theta ={\frac {\sin \theta }{\cos \theta }}=\cot \left({\frac {\pi }{2}}-\theta \right)={\frac {1}{\cot \theta }}\,}$
Cotangent	cot (or ctg)	${\displaystyle \cot \theta ={\frac {\cos \theta }{\sin \theta }}=\tan \left({\frac {\pi }{2}}-\theta \right)={\frac {1}{\tan \theta }}\,}$
Secant	sec	${\displaystyle \sec \theta ={\frac {1}{\cos \theta }}=\csc \left({\frac {\pi }{2}}-\theta \right)\,}$
Cosecant	csc (or cosec)	${\displaystyle \csc \theta ={\frac {1}{\sin \theta }}=\sec \left({\frac {\pi }{2}}-\theta \right)\,}$

1. ↑ "Comprehensive List of Algebra Symbols". Math Vault. 2020-03-25. Retrieved 2020-08-29.
2. ↑ Weisstein, Eric W. "Trigonometric Functions". mathworld.wolfram.com. Retrieved 2020-08-29.