Diketahuo titik A(1,2,3), B(5,3,6), dan C(13,5,p) segaris. Nilai p adalah?

AB
= B- A
= (4,1,3)

BC
= C - B
= (8,2,p-6)

segaris, maka
AB = k.BC
(4,1,3) = k(8,2,p-6)

8k = 4
k = 1/2


maka
1/2 (p-6) = 3
p/2 - 3 = 3
p/2 = 6
p = 12