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I don't understand the solution to question a) ii., could someone please explain it to me?

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- May 4th 2010, 05:48 AMshawlivector question - parallelogram
The question and the solution are attached in this post.

I don't understand the solution to question a) ii., could someone please explain it to me? - May 4th 2010, 08:34 AMtonio

It's just cumbersome notation: note that since ABCD is a paralellogram, it must be that $\displaystyle AD=BC\,,\, \|AD\|=\|BC\|\,,\,AD//BC\Longrightarrow \overrightarrow{AD}=\overrightarrow {BC}$ , and

putting $\displaystyle D=xi+yj$ , we get that $\displaystyle \overrightarrow{AD}=(x-4)i+(y-2)j=-6i-2j=\overrightarrow{BD}\Longrightarrow x=-2\,,\,y=0\Longrightarrow D=-2i$

Tonio - May 4th 2010, 08:44 AMshawli
Ohhh I see it ...drawing it helps.

Thank you!!