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 | | http://functions.wolfram.com/01.18.27.1654.01 | 
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 | | ArcSec[Sqrt[z^2 - 1]/Sqrt[z^2]] == (-I) ArcTanh[z] - Pi/2 /; 
 Element[z, Reals] && z < -1 | 
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 | | Cell[BoxData[RowBox[List[RowBox[List[RowBox[List["ArcSec", "[", FractionBox[SqrtBox[RowBox[List[SuperscriptBox["z", "2"], "-", "1"]]], SqrtBox[SuperscriptBox["z", "2"]]], "]"]], "\[Equal]", RowBox[List[RowBox[List[RowBox[List["-", "\[ImaginaryI]"]], " ", RowBox[List["ArcTanh", "[", "z", "]"]]]], "-", FractionBox["\[Pi]", "2"]]]]], "/;", RowBox[List["(", RowBox[List[RowBox[List["z", "\[Element]", "Reals"]], "\[And]", RowBox[List["z", "<", RowBox[List["-", "1"]]]]]], ")"]]]]]] | 
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   <math xmlns='http://www.w3.org/1998/Math/MathML' mathematica:form='TraditionalForm' xmlns:mathematica='http://www.wolfram.com/XML/'>  <semantics>  <mrow>  <mrow>  <mrow>  <msup>  <mi> sec </mi>  <mrow>  <mo> - </mo>  <mn> 1 </mn>  </mrow>  </msup>  <mo> ( </mo>  <mfrac>  <msqrt>  <mrow>  <msup>  <mi> z </mi>  <mn> 2 </mn>  </msup>  <mo> - </mo>  <mn> 1 </mn>  </mrow>  </msqrt>  <msqrt>  <msup>  <mi> z </mi>  <mn> 2 </mn>  </msup>  </msqrt>  </mfrac>  <mo> ) </mo>  </mrow>  <mo> ⩵ </mo>  <mrow>  <mrow>  <mrow>  <mo> - </mo>  <mi> ⅈ </mi>  </mrow>  <mo> ⁢ </mo>  <mrow>  <msup>  <mi> tanh </mi>  <mrow>  <mo> - </mo>  <mn> 1 </mn>  </mrow>  </msup>  <mo> ( </mo>  <mi> z </mi>  <mo> ) </mo>  </mrow>  </mrow>  <mo> - </mo>  <mfrac>  <mi> π </mi>  <mn> 2 </mn>  </mfrac>  </mrow>  </mrow>  <mo> /; </mo>  <mrow>  <mo> ( </mo>  <mrow>  <mrow>  <mi> z </mi>  <mo> ∈ </mo>  <mi> ℝ </mi>  </mrow>  <mo> ∧ </mo>  <mrow>  <mi> z </mi>  <mo> < </mo>  <mrow>  <mo> - </mo>  <mn> 1 </mn>  </mrow>  </mrow>  </mrow>  <mo> ) </mo>  </mrow>  </mrow>  <annotation-xml encoding='MathML-Content'>  <apply>  <ci> Condition </ci>  <apply>  <eq />  <apply>  <arcsec />  <apply>  <times />  <apply>  <power />  <apply>  <plus />  <apply>  <power />  <ci> z </ci>  <cn type='integer'> 2 </cn>  </apply>  <cn type='integer'> -1 </cn>  </apply>  <cn type='rational'> 1 <sep /> 2 </cn>  </apply>  <apply>  <power />  <apply>  <power />  <apply>  <power />  <ci> z </ci>  <cn type='integer'> 2 </cn>  </apply>  <cn type='rational'> 1 <sep /> 2 </cn>  </apply>  <cn type='integer'> -1 </cn>  </apply>  </apply>  </apply>  <apply>  <plus />  <apply>  <times />  <apply>  <times />  <cn type='integer'> -1 </cn>  <imaginaryi />  </apply>  <apply>  <arctanh />  <ci> z </ci>  </apply>  </apply>  <apply>  <times />  <cn type='integer'> -1 </cn>  <apply>  <times />  <pi />  <apply>  <power />  <cn type='integer'> 2 </cn>  <cn type='integer'> -1 </cn>  </apply>  </apply>  </apply>  </apply>  </apply>  <apply>  <and />  <apply>  <in />  <ci> z </ci>  <ci> ℝ </ci>  </apply>  <apply>  <lt />  <ci> z </ci>  <cn type='integer'> -1 </cn>  </apply>  </apply>  </apply>  </annotation-xml>  </semantics>  </math> 
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 | | Cell[BoxData[RowBox[List[RowBox[List["HoldPattern", "[", RowBox[List["ArcSec", "[", FractionBox[SqrtBox[RowBox[List[SuperscriptBox["z_", "2"], "-", "1"]]], SqrtBox[SuperscriptBox["z_", "2"]]], "]"]], "]"]], "\[RuleDelayed]", RowBox[List[RowBox[List[RowBox[List[RowBox[List["-", "\[ImaginaryI]"]], " ", RowBox[List["ArcTanh", "[", "z", "]"]]]], "-", FractionBox["\[Pi]", "2"]]], "/;", RowBox[List[RowBox[List["z", "\[Element]", "Reals"]], "&&", RowBox[List["z", "<", RowBox[List["-", "1"]]]]]]]]]]]] | 
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 | | Date Added to functions.wolfram.com (modification date) | 
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