document.write( "Question 109515: I want to know what will i do to prove that quadrilateral is a parallelogram.
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Algebra.Com's Answer #79834 by stanbon(75887)\"\" \"About 
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Show that opposite sides have the same slope.
\n" ); document.write( "If they do, they are parallel.
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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