document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=43450>Question 43450</A>: <I><SPAN STYLE=\"word-break: break-all;\">  Tell whether the points are the vertices of a parallelogram (that is not a rectangle), a rectangle, or neither.\r<BR>\n" );
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document.write( "(-7, -1), (2, -10), (16, -3), (7, 8) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #28553 by </B><A HREF=/tutors/aboutme.mpl?userid=psbhowmick><B>psbhowmick(878)</B></A><img src=\"/images/stars/stars-11.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=psbhowmick><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=psbhowmick><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=28553\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let the points be A (-7, -1), B (2, -10), C (16, -3) and D (7, 8).\r<BR>\n" );
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document.write( "Slope of AB = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28-1+-+%28-10%29%29%2F%28-7+-+2%29 ALIGN=MIDDLE  ALT=\"%28-1+-+%28-10%29%29%2F%28-7+-+2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28-1%2B10%29%2F%28-9%29 ALIGN=MIDDLE  ALT=\"%28-1%2B10%29%2F%28-9%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-+9%2F9 ALIGN=MIDDLE  ALT=\"-+9%2F9\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-1 ALIGN=MIDDLE  ALT=\"-1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Slope of BC = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28-10-%28-3%29%29%2F%282-16%29 ALIGN=MIDDLE  ALT=\"%28-10-%28-3%29%29%2F%282-16%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28-10%2B3%29%2F%28-14%29 ALIGN=MIDDLE  ALT=\"%28-10%2B3%29%2F%28-14%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+7%2F14 ALIGN=MIDDLE  ALT=\"+7%2F14\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F2 ALIGN=MIDDLE  ALT=\"1%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Slope of CD = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28-3+-+8%29%2F%2816+-+7%29 ALIGN=MIDDLE  ALT=\"%28-3+-+8%29%2F%2816+-+7%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-11%2F9 ALIGN=MIDDLE  ALT=\"-11%2F9\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Slope of AB = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%288+-+%28-1%29%29%2F%287+-%28-7%29%29 ALIGN=MIDDLE  ALT=\"%288+-+%28-1%29%29%2F%287+-%28-7%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%288%2B1%29%2F%287%2B7%29 ALIGN=MIDDLE  ALT=\"%288%2B1%29%2F%287%2B7%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+9%2F14 ALIGN=MIDDLE  ALT=\"+9%2F14\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "For a quadrilateral to be a parallelogram, the opposite sides must be parallel and their slopes have to be equal.<BR>\n" );
document.write( "So, here, slopes of AB and CD must be equal and also slopes of AC and BD must be equal.<BR>\n" );
document.write( "Clearly, this is not the case.<BR>\n" );
document.write( "Hence the given points does not form a parallelogram and so no question of rectangle.  </SPAN>\n" );
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