Given a rectangular parallelepiped $ABCDA_1B_1C_1D_1$, which has $AD= DC = 3\sqrt2$ cm, and $DD_1 = 8$ cm. Through the diagonal $B_1D$ of the parallelepiped $m$ parallel to line $A_1C_1$ is drawn on the plane $\gamma$. a) Draw a section of a parallelepiped with plane $\gamma$. b) Justify what geometric figure is this section, and find its area. (Alexander Shkolny)