With respect to a fixed origin O, the line l1 has vector equation
r = (-9x, 8y, 5z) + u(5x, -4y, -3z)
where u is a scalar parameter
The point A is on l1 where u=2
(a) write down the coordinates of A (I got this one)
The acute angle between OA and l1 is θ, where O is the origin
(b)Find the value of cosθ
The point B such that OB=3OA
The line l2 passes through point B and is parallel to l1
(c) Find a vector equation for l2
(d)Find the length of OB, as a surd
The pount X lies on l2. Given that the vector OX is perpendicular to l2,
(e) find the length of OX, giving your answer to 3 s f.
question has total of 10 marks