arsinh x = ln ⁡ ( x + x 2 + 1 ) {\displaystyle \operatorname {arsinh} \,x=\ln \left(x+{\sqrt {x^{2}+1}}\right)} arcosh x = ln ⁡ ( x + x 2 − 1 ) ; x ≥ 1 {\displaystyle \operatorname {arcosh} \,x=\ln \left(x+{\sqrt {x^{2}-1}}\right);x\geq 1} artanh x = 1 2 ln ⁡ 1 + x 1 − x ; | x | < 1 {\displaystyle \operatorname {artanh} \,x={\tfrac {1}{2}}\ln {\frac {1+x}{1-x}};\left|x\right|<1} arcoth x = 1 2 ln ⁡ x + 1 x − 1 ; | x | > 1 {\displaystyle \operatorname {arcoth} \,x={\tfrac {1}{2}}\ln {\frac {x+1}{x-1}};\left|x\right|>1} arsech x = ln ⁡ 1 + 1 − x 2 x ; 0 < x ≤ 1 {\displaystyle \operatorname {arsech} \,x=\ln {\frac {1+{\sqrt {1-x^{2}}}}{x}};0<x\leq 1} arcsch x = ln ⁡ ( 1 x + 1 + x 2 | x | ) {\displaystyle \operatorname {arcsch} \,x=\ln \left({\frac {1}{x}}+{\frac {\sqrt {1+x^{2}}}{\left|x\right|}}\right)}