Mainly to test what a vector is-follow the parallelogram rule.

calculate

Let a=(x, y) and b=(x', y').

1, vector addition

The addition of vectors satisfies parallelogram rule and triangle rule. Vector addition

OB+OA=OC .？ a+b=(x+x '，y+y ').？ a+0=0+a=a .？ Algorithm of vector addition:? Exchange law: a+b = b+a; ? Law of association: (a+b)+c=a+(b+c). ?

Look at the picture. Is that clear? But I seriously doubt that this is a mid-term exam? There seems to be no content about vector parallelogram rule in junior middle school books ~ ~ ~ This question is very biased. Have you never seen such a question in Ningbo's middle school examination paper? Is there anything similar in the students' papers that came in? I'm going to take an interview exam in May 12? I wish you progress in your studies.