document.write( "Question 787151: Is quadrilated ABCD with the given verticles A(1,2) B(2,5) C(5,7) D(4,4) a parallelogram? \n" ); document.write( "
Algebra.Com's Answer #478108 by Cromlix(4381)\"\" \"About 
You can put this solution on YOUR website!
Using the gradient formula:
\n" ); document.write( "y2 - y1/ x2 - x1
\n" ); document.write( "The gradient of AB =
\n" ); document.write( "5 - 2/2 - 1
\n" ); document.write( "= 3
\n" ); document.write( "The gradient of DC =
\n" ); document.write( "7 - 4/5 - 4
\n" ); document.write( "= 3
\n" ); document.write( "The gradient of AD =
\n" ); document.write( "4 - 2/4 - 1
\n" ); document.write( "= 2/3
\n" ); document.write( "The gradient of BC =
\n" ); document.write( "7 - 5/5 - 2
\n" ); document.write( "= 2/3
\n" ); document.write( "As the gradients of AB = DC
\n" ); document.write( "and AD = BC
\n" ); document.write( "then quadrilateral ABCD
\n" ); document.write( "is a parallelogram.
\n" ); document.write( "Hope this helps.
\n" ); document.write( ":-)
\n" ); document.write( " \n" ); document.write( "
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