document.write( "Question 922220: three vertices of a quadrilateral are (-1,-1) (1,2) and (5,-1)
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Algebra.Com's Answer #559455 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "You take any two of the points, and observe how you get from one to\r\n" );
document.write( "the other by moving horizontally or vertically so many units. Then\r\n" );
document.write( "you start at the third point and move the same number of units\r\n" );
document.write( "horizontally and vertically and you'll end up at a fourth point.\r\n" );
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document.write( "There are three possible fourth points that form a parallelogram with\r\n" );
document.write( "the other three. \r\n" );
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document.write( "If we start at (-1,1) and go to (1,2) we notice that we have to move 2 units\r\n" );
document.write( "right and then move 3 units up.\r\n" );
document.write( "Now we start at (5,-1) and do the same thing.  That is, we move 2 units right\r\n" );
document.write( "and then 3 units up. We then end up at (7,2), the point in red, and draw\r\n" );
document.write( "the parallelogram (in green):\r\n" );
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document.write( "If we start at (5,-1) and go to (-1,-1) we notice that we have to move 6 units\r\n" );
document.write( "left (and NO units up).\r\n" );
document.write( "Now we start at (1,2) and do the same thing.  That is, we move 6 units left\r\n" );
document.write( "(and NO units up). We then end up at (-5,2), the point in red, and we draw\r\n" );
document.write( "the parallelogram (in green):\r\n" );
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document.write( "------------------------------\r\n" );
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document.write( "If we start at (1,2) and go to (-1,1) we notice that we have to move 2 units\r\n" );
document.write( "left and 3 units down.\r\n" );
document.write( "Now we start at (5,-1) and do the same thing.  That is, we move 2 units left\r\n" );
document.write( "and 3 units down. We then end up at (3,-4), the point in red, and we draw\r\n" );
document.write( "the parallelogram (in green):\r\n" );
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document.write( "Just for fun, let's look at all of them on one graph:\r\n" );
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document.write( "Edwin
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