Flächeninhalt verallgemeinerter hyperbolischer Dreiecke

The purpose of this note is to extend the notion of hyperbolic area to polygons lying anywhere in a projective plane equipped with a hyperbolic metric. Since such polygons can be triangulated by right triangles, we restrict our discussion to right triangles. In general, the surface area is a complex number; monotonicity of the area functional is therefore not to be expected. However, the defect formula holds in all cases.