It is known that | OA | = | ob | = | OC |. The angle between OA, OB and OC is 120 ° and OA + ob + OC (both vectors) is calculated

It is known that | OA | = | ob | = | OC |. The angle between OA, OB and OC is 120 ° and OA + ob + OC (both vectors) is calculated

Vector OA + vector 0b is equal to a vector which is 180 ° to vector OC and is equal to vectors OA and ob
OA | = | ob | = | OC |,
So the vector OC plus this vector gives the zero vector