Determine the volume of the parallelopiped of Fig. 3.25 when

(a) P = (3 in).i − (4 in.)j + (1 in.) k, Q = − (7 in.)i + (6 in.)j − (8 in.)k, S = (9 in.)i − (2 in.)j − (3 in.)k,

(b) P= − (5 in.)i − (7 in.) j + (4 in.) k, Q = (6 in.)i − (2 in.)j + (5 in.) k, S= − (4 in.)i + (8 in.) j − (9 in.) k.