Find the projection of `veca` on `vecb` if `veca`. `vecb` =8 and `vecb` = `2hati +6 hatj+3hatk `

Answer

a

Explanation

`(veca_(k)xxveca_(k+1))-r^(2)sin""(2pi)/n`
`veca_(k).veca_(k+1)=r^(2)cos"" (2pi)/n`
Given `|underset(k=1)overset(n-1)sumveca_(k)xxveca_(k+1)| = |underset(k+1)overset(n-1)suma_(k).a_(k+1)|`
`Rightarrow r_(2) (n-1)sin"" (2pi)/n = r^(2)(n-1) cos ""(2pi)/n`
`Rightarrow tan "" (2pi)/n=1`
` Rightarrow (2pi)/n = kpi + pi/4, k in Z`
`Rightarrow n = 8/(4k=1) `
`Rightarrow` n=8 ( when k =0)
Note: solutions of the remaining parts are given in their respective chapters.