  In this work we present a generalized Laplace method for a formal, simple,
quasi-classical, determination of the outer and inner horizon radius of
Kerr-Newman black hole. We consider classical gravitational interaction between
a thin, with homogeneously distributed mass and electric charge, spherical
(black) shell and a probe particle. Also, we use relativistic equivalence
principle. Finally we suppose that probe particle propagates radially to shell
with speed of light while tangentially it rotates in common with shell, so that
total energy of a probe particle equals zero.
