document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1137256>Question 1137256</A>: <I><SPAN STYLE=\"word-break: break-all;\"> is the quadrilateral with the given vertices a parallelogram when using<BR>\n" );
document.write( "coordinate geometry?\r<BR>\n" );
document.write( "\n" );
document.write( "(1,4),  (4,4),  (5,1),  (2,1) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #755112 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52908)</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=755112\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "The points (1,4) and (4,4) have equal y-coordinate y = 4, so they lie on the horizontal line parallel to x-axis.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "The length of the side between these two pints is  the difference of their x-coordinates  4 - 1 = 3.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "The points (5,1) and (2,1) have equal y-coordinate y = 1, so they lie on the horizontal line parallel to x-axis.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "The length of the side between these two pints is  the difference of their x-coordinates  5 - 2 = 3.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "So, the given quadrilateral has two the opposite sides parallel and of equal length.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "It implies that the quadrilateral is a parallelogram.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "See the lesson\r<BR>\n" );
document.write( "\n" );
document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=http://www.algebra.com/algebra/homework/Parallelograms/Properties-of-the-sides-of-parallelograms.lesson>Properties of the sides of parallelograms</A> \r<BR>\n" );
document.write( "\n" );
document.write( "in this site.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Also, &nbsp;you have this free of charge online textbook on Geometry\r<BR>\n" );
document.write( "\n" );
document.write( "&nbsp;&nbsp;&nbsp;&nbsp;<A  rel=nofollow HREF=https://www.algebra.com/algebra/homework/Triangles/GEOMETRY-your-online-textbook.lesson>GEOMETRY - YOUR ONLINE TEXTBOOK</A> \r<BR>\n" );
document.write( "\n" );
document.write( "in this site.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "The referred lesson is the part of this textbook under the topic \"<U>Properties of parallelograms</U>\".\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Save the link to this online textbook together with its description\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Free of charge online textbook in GEOMETRY<BR>\n" );
document.write( "https://www.algebra.com/algebra/homework/Triangles/GEOMETRY-your-online-textbook.lesson\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "to your archive and use it when it is needed.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );