If we reflect this solution through the $y$-axis passing through the rightmost point of the constant state labelled $C$, we obtain a solution for a body containing two cracks lying on the $x$-axis with crack tips equidistant from the $y$-axis and with the slip-line fields meeting at the origin. Assuming the rigidly deforming parts of the body in the region of positive (resp., negative) $y$ to move vertically with velocity $V$ (resp., $-V$ ), use the Geiringer equations (7.90) to show that a tangential velocity discontinuity occurs on the curves separating the rigid and plastic portions of the body.