Question

Show that the vector 2i - j + k and i - 3j - 5k are at right angles.

Answer 1

Let vector a = 2i - j + k

and vector b = i - 3j - 5k

Now, |vector a| = √(22 + (-1)2 + 12) = √6

and |vector b| = √(12 + (-3)2 + (-5)2) = √35

vector(a.b) = 2 x 1 + (-1) x (-3) + 1(-5) = 0

Hence, given vectors are at right angles.