5. Relative to a fixed origin O, the vector equations of the two lines l1 and l2 are l1: r = 9i + 2j + 4k + t(–8i – 3j + 5k), and l2: r = –16i + aj + 10k + s(i – 4j + 9k), where a is a constant. The two lines intersect at the point A.
(a) Find the value of a. (6)
(b) Find the position vector of the point A. (1)
(c) Prove that the acute angle between l1 and l2 is 60°.
Point B lies on l1 and point C lies on l2. The triangle ABC is equilateral with sides of length 14Ö2.
(d) Find one of the possible position vectors for the point B and the corresponding position vector for the point C
parts a,b,c no problemo. Part D slightly confused although i can do part of it just not sure.
a) -3
b) -15i,-7j+19k
c)show that,
Please help!