Аннотация:The geometry of a hyperbolic plane H^ of positive curvature can be realized on ideal domain of
the Lobachevskii plane L^2. The planes H^ and L^2 are components of an extended hyperbolic plane
H^2, i.e. the projective plane P_2 with the oval curve γ fixed on it. In this article the formula of
expression of the area of the generalized polygon without parabolyc edges on the plane bH through
measures of its internal angles is proved.