Vector CM= vector CB+ vector BM= vector CM- vector CB

In the delta delta cam

Vector CM= vector CA+ vector AM = vector CM- vector CA

Vector AM=λ vector MB

Vector AM+λ vector BM =0 vector

λ vector BM=λ vector CM-λ vector CB

Vector AM= vector CM- vector CA addition

(1+λ) vector CM=λ vector CB+ vector CA

Vector CM=λ/( 1+λ) vector CB+ 1/( 1+λ) vector CA.

therefore

x=λ/( 1+λ)

y= 1/( 1+λ)

x+y= 1