coshz=ez+e−z2
sinhz=ez−e−z2
coshiz=cosz
sinhiz=isinz
tanhiz=itanz
cosh(x+y)=coshxcoshy+sinhxsinhy
sinh(x+y)=sinhxcoshy+coshxsinhy
cosh(x−y)=coshxcoshy−sinhxsinhy
sinh(x−y)=sinhxcoshy−coshxsinhy