shock waves interaction

huangyhg

shock waves interaction
this question is easier to pose referring to the book by d.a.anderson "modern compressible flow". it concerns the example for the intersection of shocks of the same family, in a double corner (figure 4.21, page 126, second edition).
the reflected wave, e, is necessary to adjust the pressures, ensuring that p5=p4. we also impose that the angles theta5 and theta4 are equal. nevertheless, both these angles are different from theta3 (the reflected wave changes the flow direction, which was parallel to the wall, in region 3), which means that the flow in region 4 is not paralel to the wall. how can that be? are there any other shocks to account for this?