Prove with vector method: the bisection sum of two diagonals of parallelogram is equal to twice of the square sum of two adjacent sides If the title, the best process Thank you! On the first floor Is the vector method that simple? ==|||I feel the process is so short No Of course, I think it's better to be short But the teacher won't let me But forget it Thank you for your quick answer ==|||I hate winter vacation homework Ah, ah

AB + AC = ad, AB-AC = BC, add the squares
Of course, short point is not good?

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