  The strongly interacting Quark-Gluon-Plasma (sQGP) created in relativistic
nucleus-nucleus collisions, can be described by hydrodynamic models. Low energy
hadrons are created after the so called freeze-out of this medium, thus their
distributions reveal information about the final state of the sQGP. Photons are
created throughout the evolution, so their distributions carry information on
the whole expansion and cool down. We show results from an analytic, 1+3
dimensional perfect relativistic hydrodynamic solution, and compare hadron and
photon observables to RHIC data. We extract an average equation of state of the
expanding quark matter from this comparison. In the second part of this paper,
we generalize the before mentioned analytic solution of relativistic perfect
fluid hydrodynamics to arbitrary temperature-dependent Equation of State. We
investigate special cases of this class of solutions, in particular, we present
hydrodynamical solutions with an Equation of State determined from lattice QCD
calculations.
