  In the paper, an approach for the numerical solution of stationary nonlinear
Navier-Stokes equations in rotation and convective forms in a polygonal domain
containing one reentrant corner on its boundary, that is, a corner greater than
${\pi}$ is considered. The method allows us to obtain the 1st order of
convergence of the approximate solution to the exact one with respect to the
grid step h, regardless of the reentrant corner value.
