document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1173738>Question 1173738</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Prove that quadrilateral A(1,2), B(2,5), C(5,7), D(4,4) is a parallelogram by using slopes. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #799036 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52921)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=799036\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .\r<BR>\n" );
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document.write( "Calculate the slopes of opposite sides  AB  and  DC and compare.\r<BR>\n" );
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document.write( "Calculate the slopes of opposite sides  BC  and  AD and compare.\r<BR>\n" );
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document.write( "If the slopes are equal in pairs, then the quadrilateral is a parallelogram.\r<BR>\n" );
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document.write( "I hope you are able to do the rest without my help.\r<BR>\n" );
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