Tangent is a trigonometric function.
tan θ = sin θ cos θ = cot ( π 2 − θ ) = 1 cot θ {\displaystyle \tan \theta ={\frac {\sin \theta }{\cos \theta }}=\cot \left({\frac {\pi }{2}}-\theta \right)={\frac {1}{\cot \theta }}\,}
