Given lines are
2x−1=−7y+8=5z−4 and
2x−1=1y−2=−3z−6
Corresponding vectors are:
a=i^−8j^+4k^, p=2i^−7j^+5k^
b=i^+2j^+6k^, q=2i^+j^−3k^
S.D.=∣p×q∣∣a−bpq∣
a−b=−10j^−2k^
[a−bpq]=∣022−10−71−25−3∣
=0−(−10)(−6−10)+(−2)(2+14)
=0−160−32=−192
∣[a−bpq]∣=192
p×q=∣i^22j^−71k^5−3∣
=i^(16)−j^(−16)+k^(16)
=16(i^+j^+k^)
∣p×q∣=163
S.D.=∣p×q∣∣a−bpq∣=163192=312=43