Once we’ve defined arccosh and square root carefully, we can see that the expressions Mathematica returns for sinh(arccosh(x)) and tanh(arccosh(x)) are correct for all complex inputs, while the simpler expressions in the table above implicitly assume we’re working with values of x for which arccosh(x) is real.
Москвичей предупредили о возвращении морозов20:14
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Артём Верейкин (Ночной линейный редактор)