(a) Given that, two particles P and Q located at the points with coordinate ˙P(t,t3−16t−3), Q(t+1,t3−6t−6) are moving in a plane. Thus, PQ‌=√(t+1−t)2+(t3−6t−6−t3+16t+3)2 ‌=√1+(10t−3)2 ∴(PQ)2‌=1+(10t−3)2≥1 Thus, minimum value of PQ is 1 .