Find the projection of `veca=2hati-hatj+hatk and vecb=hati-2hatj+hatk.`

Explanation

projectin of A on B=A`cos theta(theta=`angle between Aand B )
`=(A.B)/(B)=(2hati-hatj+hatk).((hati-2hatj+hatk))/(sqrt((1)^(2)+(-2)^(2)+(1)^(2)))=(2+2+1)/(sqrt(6))=(5)/(sqrt(6))`