It is shown that the equations of unsteady, nonlinear, nonviscous, nonheat-conducting flow may be put in a conical form. The problem of a shock striking an infinite wedge is considered. An invariance relation is established, and certain properties of the reflected shock are examined. These include a discussion of a possible form of reciprocal flows; a calculation indicating the impossibility of a certain reflected shock shape for air; and, based upon an analysis of the characteristics of the flow, a nonexistence proof for certain combinations of shock strengths and wedge angles.