cot(a)=19.08

That is one of the answers. :)

$${cot}{\left({\mathtt{a}}\right)} = {\mathtt{19.08}} \Rightarrow {\mathtt{a}} = {\frac{{\mathtt{180}}{\mathtt{\,\times\,}}{acot}{\left({\frac{{\mathtt{477}}}{{\mathtt{25}}}}\right)}}{{\mathtt{\pi}}}} \Rightarrow {\mathtt{a}} = {\mathtt{171.897\: \!559\: \!990\: \!574\: \!621\: \!9}}$$