Linear algebra Do both part i and part ii I have found part

Linear algebra. Do both part i and part ii. I have found part i and wanted to check my work. Part ii im severly confused about.

3. Let a= | 3 (i) Compute the perpendicular projection of the vector b1on the line in the direction 2 of a. (ii) Write a formula for the distance of the point Xa to the point b. Show that this distance attains the minimum value when a_ p is the perpendicular projection found in (i).

Solution

Projection of b in the direction of a=(a dot b)

                                                 =(1 3 -2) dot (0 1 2)

                                                 =(1*0)+(3*1)+(-2*2)

                                                 =0+3-4

                                                 =-1

a dot a=(1^2)+(3^2)+(-2^2)

          =1+9+4

          =14

now [(a dot b)/a dot a]=-1/14

now {[(a dot b)/a dot a]}b=(-1/14)(0, 1, 2)

                                    =(0,-1/14,-2/14)