Hyperbolic function, its derivative and inverse
Hyperbolic function:
In mathematics, hyperbolic functions are analogues of the ordinary trigonometric functions, but defined using the hyperbola rather than the circle. Just as the points (cos t, sin t) form a circle with a unit radius, the points (cosh t, sinh t) form the right half of the unit hyperbola.
Sinh(-x)=-sinhx
Cosh(-x)=coshx
Cosh2x+sinh2x=cosh 2x
Sinh2x=2 sinhx.coshx
Cosh(x+y)=coshx.coshy+sinhx.sinhy
Sinh(x+y)=sinhx.coshy+coshx.sinhy