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Knowing that ABCD parallelogram, find the real numbers a,b,c, so that D to be the...

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teahottea | Student, Undergraduate | eNotes Newbie

Posted May 31, 2009 at 7:35 PM via web

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Knowing that ABCD parallelogram, find the real numbers a,b,c, so that D to be the center weight of the points system (A,a),(B,b),(C,c).

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giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted June 1, 2009 at 1:40 AM (Answer #1)

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We'll search a link between DA, DB and DC (considered as vectors). But ABCD is a parallelogram and vectors composition says, in this case,DA+DC=DB.

So, DA-DB+DC=0  and 1+1-1 different from 0, so the point D is the center of weight for (A,1),(B,-1),(C,1).

It is important to mention that one of the most significant step in demonstrating that D is the center of weight for (A,a),(B,b),(C,c) was to prove that a+b+c different from 0.

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