kappa=6.67 (10^(-11));
M=6 (10^24);
T=24 3600;
R=6.378 (10^6);

velikostpisma=14;

funkce[fi_]:=ArcCot[((kappa M (T^2))/(2(π^2)(R^3)Sin[2fi]))-Cot[fi]] (180/π);
Plot[funkce[fi Degree],{fi,-90,90},PlotStyle->{Blue,Thickness[0.006]},Exclusions->{0},AxesOrigin->{0,0},AxesLabel->{Style["(φ/°)",velikostpisma,Black,FontFamily->Times],Style["(α/°)",velikostpisma,Black,FontFamily->Times]}]