Find the unit vector parallel to the resultant vector of `2hati+4hatj-5hatk and hati+2hatj+3hatk`.

Explanation

Resultant vector, `r=(2hati+4hatjj-5hatk)+(hati+2hatj+3hatk)`
`=3hati+6hatj-2hatk`
Unit vector parallel to `r=(1)/(|r|)r`
`=(1)/(sqrt(3^(2)+6^(2)+(-2)^(2)))(3hati+6hatj-2hatk)`
`=(1)/(7)(3hati+6hatj-2hatk)`