(a) Sketch three-dimensional views of the unit cell of a b.c.c. crystal, showing a (100) plane, a (110) plane, a (111) plane and a (210) plane. (b) The slip planes of b.c.c. iron are the {110} planes: sketch the atom arrangement in these planes, and mark the <111> slip directions. (c) Sketch three-dimensional views of the unit cell of an f.c.c. crystal, showing a [100], a [110], a [111] and a [211] direction. (d) The slip planes of f.c.c. copper are the {111} planes: sketch the atom arrangement in these planes and mark the <110> slip directions.