  The set of the nonlinear Ginzburg-Landau equations is solved for an Al
mesoscopic superconducting triangle of finite thickness. We calculate the
distributions of the superconducting phase in the triangle and of the magnetic
field in and near the triangle. The distribution of the superconducting phase
in the triangle is studied as a function of the applied magnetic field.
Possible scenarios of penetration of the magnetic field into the triangle are
analyzed. We consider two different states: a single vortex state and a state
in the form of a symmetric combination of three vortices and an antivortex with
vorticity L_a = - 2 ("3 - 2" combination). The free energy calculations show
that a single vortex penetrates the triangle through a midpoint of one side.
The "3 - 2" combination turns out to be thermodynamically preferable when the
vortices are close to the center of the triangle. Equilibrium is achieved when
a single vortex (or each component of the "3 - 2" combination) is in the center
of the triangle.
