Question

Find a unit vector perpendicular to each of the vectors (a + b) and (a - b), where vector a = i + j + k, vector b = i + 2j + 3k.

Answer 1

We have vector (a + b) = 2i + 3j + 4k and vector (a - b) = - j - 2k

A vector which is perpendicular to both vector (a + b) and vector (a - b) is given by

Therefore, the required unit vector is