prove that the vectors `A=2hati-3hatj+hatk and B=hati+hatj + hatk` are mutually perpendicular .

Explanation

`A.B=(2hati-3hatj+hatk).(hati+hatj+hatk)`
`=(2)(1)+(-3)(1)+(1)(1)`
`=0=ABcos theta`
`thereforecostheta=O (asAneO, bne O)`
or the vectors A and Bare mutually perpendicular.