That's right. Vector operations are similar to algebraic operations, and there are also complete square formulas and square variance formulas.

(vector a+ vector b)? = vector a? +2 vector a* vector b+ vector b? Yes,

Vector a? =|a|？ , vector b? =|b|？ , vector a* vector b = | a | | b | * cos

The result is quantity.

If you want to prove it, you must use the vector parallelogram rule.