document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=256201>Question 256201</A>: <I><SPAN STYLE=\"word-break: break-all;\"> how can I tell if two lines are perpendicular?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #188368 by </B><A HREF=/tutors/aboutme.mpl?userid=drk><B>drk(1908)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=drk><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=188368\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> find the slopes of the two lines. There are 3 ways to tell if they are perpendicular: <BR>\n" );
document.write( "(1) graph then and if they cross at right angles, they are perpendicular.<BR>\n" );
document.write( "(2) multiply the two slopes. If the product is -1, then they are perpendicular<BR>\n" );
document.write( "(3) If the slope of one is the negative flip of the slope of the second, then they are perpendicular. </SPAN>\n" );
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