A (vector A- vector b) times vector C= (vector A- vector AD) times vector C= vector DB times vector C=0.

B (vector A+ vector B- vector C) times vector A= vector 0 times vector A=0.

Modular multiplication vector A= (modulus of vector C-modulus of vector B) C (vector A- vector C) times vector A=0 times vector A= vector 0.

The modulus of d (vector A+ vector B+ vector c) =2* (modulus of vector c) =2√2.