Answer to Question #65730 in Math for Manpreet Singh

Question

Let A = 5i − j + k, B = j − 5k, C = −15i + 3 j − 3k be three vectors. Which pair of
vectors are
i) perpendicular? ii) parallel?

Answer 1

i) AB=5*0-1*1+1*(-5)=-6.
AC=5*(-15)-1*3+1*(-3)=-81.
BC=0*(-15)+1*3-5*(-3)=18.
There is no pair of perpendicular vectors.

ii) C=-3A. Vectors A and C are parallel.