document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=389908>Question 389908</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find the x and y coordinates of the points on x^2 + y^2=16 at which the tangent line(s) are:   \r<BR>\n" );
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document.write( "a) horizontal                             b) have a slope of 1 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #277620 by </B><A HREF=/tutors/aboutme.mpl?userid=robertb><B>robertb(5830)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=robertb><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=robertb><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=277620\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a) The tangent lines are horizontal at the points (0,4) and (0,-4).\r<BR>\n" );
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document.write( "b) The tangent lines have slope 1 at the intersection points of the circle with the line y = -x.  Solving:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5E2+%2B+y%5E2+=+x%5E2+%2B+%28-x%29%5E2+=+2x%5E2+=+16 ALIGN=MIDDLE  ALT=\"x%5E2+%2B+y%5E2+=+x%5E2+%2B+%28-x%29%5E2+=+2x%5E2+=+16\"   DISABLED_style= \"max-width:90%; height:auto;\" > ==> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5E2+=+8 ALIGN=MIDDLE  ALT=\"x%5E2+=+8\"   DISABLED_style= \"max-width:90%; height:auto;\" >, or <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+2sqrt%282%29 ALIGN=MIDDLE  ALT=\"x+=+2sqrt%282%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=++-2sqrt%282%29 ALIGN=MIDDLE  ALT=\"x+=++-2sqrt%282%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( "Then the points are (<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2sqrt%282%29 ALIGN=MIDDLE  ALT=\"2sqrt%282%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >,<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+-2sqrt%282%29 ALIGN=MIDDLE  ALT=\"+-2sqrt%282%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >) and (<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-2sqrt%282%29 ALIGN=MIDDLE  ALT=\"-2sqrt%282%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >,<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+2sqrt%282%29 ALIGN=MIDDLE  ALT=\"+2sqrt%282%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >). </SPAN>\n" );
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