Question

Given that A = i+ a j + k and B = a i+ j + k, if A and B are normal to each other, what is a?

Answer 1

`a=-1/2`.

Explanation:

The sufficient condition for perpendicularity is the dot (scalar)

product

`A.B=(1)(a)+(a)(1)+(1)(1)=2a+1=0`

So, `a = -1/2`.