I'm not sure if I should've started a new thread for this but..(adsbygoogle = window.adsbygoogle || []).push({});

I need some help trying to prove that the diagonals of a parallelogram bisect each other..

I think I have an idea of how to solve this but I can't seem to put it together:

Given

AB = DC

AD = BC

Known

AB + BC = AC

BC + BD = BD

and so forth..

I'm trying to prove that BZ = ZD and AZ = ZC. Using position vectors, I determined that the midpoint of vector AC to be OA + OB/2 = OZ and that AZ = OA - OZ and ZC = OZ - OC. I had the train of thought in my mind on how to persue this problem before but I lost it somehow after thinking too hard. I know these are the right steps that need to be considered to finish the problem, but in what steps do I need to do in order to finish this problem?

http://img175.imageshack.us/img175/1889/46wf.th.jpg [Broken]

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# Vector Proofs: A Quadrilateral thing #2!

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