Let `veca vecb and vecc` be three non-zero vectors such that `veca + vecb + vecc = vec0 and lambda vecb xx veca xx veca + vecbxxvecc + vecc + veca = vec0` then find the value of `lambda`.

Explanation

Clearly, `veca , vecb and vecc` respesent the sides of a tirangle,
`Rightarrow veca xx vecb =vecc xx veca `
`or veca xxvecb + vecc + vecb xx vecc xx veca = 3veca xx vecb`
`or 2vecb xx veca +vecb xx vecc + vecc xx veca = 0 Rightarrow lambda=2`