document.write( "Question 122273: Points X (-1,1),Y (3,5), and Z (17,1), are the coordinates of three vertices of a parallelogram. What are the possible coordinates of W, the fourth vertex? \n" ); document.write( "
Algebra.Com's Answer #89775 by psbhowmick(878)\"\" \"About 
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Let the coordinates of W be (h,k).
\n" ); document.write( "The opposite sides of a parallelogram are parallel and hence their slopes must be equal.
\n" ); document.write( "Slope of WX = Slope of YZ
\n" ); document.write( "i.e. \"%28k-1%29%2F%28h-%28-1%29%29+=+%285+-+1%29%2F%283+-+17%29\"
\n" ); document.write( "i.e. \"%28k-1%29%2F%28h%2B1%29+=+-4%2F14+=+-2%2F7\"
\n" ); document.write( "i.e. \"7%28k-1%29+=+-2%28h%2B1%29\"
\n" ); document.write( "i.e. \"2h+%2B+7k+=+5%29\" __________ (1)\r
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\n" ); document.write( "\n" ); document.write( "Slope of ZW = Slope of XY
\n" ); document.write( "i.e. \"%28k-1%29%2F%28h-17%29+=+%285-1%29%2F%283-%28-1%29%29\"
\n" ); document.write( "i.e. \"%28k-1%29%2F%28h-17%29+=+4%2F4+=+1\"
\n" ); document.write( "i.e. \"%28k-1%29+=+%28h-17%29\"
\n" ); document.write( "i.e. \"h+-+k+=+16\" _________ (2)\r
\n" ); document.write( "\n" ); document.write( "Solving (1) and (2)
\n" ); document.write( "h = 13
\n" ); document.write( "k = -3\r
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\n" ); document.write( "\n" ); document.write( "Hence, the coordinates of W are (13, -3).
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