document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=768349>Question 768349</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Prove that the points A(-4,-1), B(-2,-3), C(4,3), and D(2,5) are the vertices of a rectangle. Sketch the rectangle. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #468239 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=468239\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Prove that the points A(-4,-1), B(-2,-3), C(4,3), and D(2,5) are the vertices of a rectangle. Sketch the rectangle.<BR>\n" );
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document.write( "Find the slope of AB, BC, CD and AD<BR>\n" );
document.write( "If the lines are perpendicular, it's a rectangle.<BR>\n" );
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document.write( "For AB:<BR>\n" );
document.write( "slope m = diffy/diffx = -2/2 = -1<BR>\n" );
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document.write( "For BC:<BR>\n" );
document.write( "m = 6/6 = 1<BR>\n" );
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document.write( "The 2 slopes are negative reciprocals, so they're perpendicular.<BR>\n" );
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document.write( "Do the same for the others. </SPAN>\n" );
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