find the angle between the vectors `vec a= 3` `hat i`+2 `hat k` and
`vec b = 2 hat i` -2 `hat j` + 4 `hat k`

Explanation

Since `veca,vecb and vecc` are non - coplanar, vectors `vecaxxvecb,vecb xxveccandveccxxveca` are also non-coplanar. Let
`vecd=l(vecbxxvecc)+vecm(veccxxveca)+vecn(vecaxxvecb)`
now multiplying both sides of (i) scalarly by `veca` we have
`veca.vecd=lveca.(vecbxxvecc)+mveca.(veccxxveca)+nveca.(vecaxxvecb)=l[vecavecc veca]([veca vecc veca]=0=[veca veca vecb])`
`l=(veca.vecd)//[veca vecb vecc]`
putting these values oif l,nm and n and (i) , we get the required relation.