document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=117909>Question 117909</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0131430734/algebrahomeworkh>Algebra and Trigonometry (Sullivan)</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> I need to find the general form of the equation of a circle. The problem in the book is \"find center at the point (-3,1) and tangent to the y-axis. Im taking a correspondence course and am having difficulty with the tangent part of the problem. Cheers! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #85893 by </B><A HREF=/tutors/aboutme.mpl?userid=Earlsdon><B>Earlsdon(6294)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Earlsdon><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=85893\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Find the equation of a circle tangent to the y-axis and whose center is at (-3, 1).\r<BR>\n" );
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document.write( "The standard form for a circle of radius r and center at (h, k) is given by:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28x-h%29%5E2+%2B+%28y-k%29%5E2+=+r%5E2 ALIGN=MIDDLE  ALT=\"%28x-h%29%5E2+%2B+%28y-k%29%5E2+=+r%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "You are given the center (h, k) as (-3, 1), so h = -3, and k = 1\r<BR>\n" );
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document.write( "Now for the radius, r:<BR>\n" );
document.write( "Any line that is tangent to (touching) a circle is perpendicular to the radius of the circle.<BR>\n" );
document.write( "Since the given circle is tangent to (touching) the y-axis, you know that the radius of the circle is perpendicular to the y-axis and you also know that center is at (-3, 1), so the radius is 3.<BR>\n" );
document.write( "Now you can write the equation:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28x-%28-3%29%29%5E2+%2B+%28y-1%29%5E2+=+3%5E2 ALIGN=MIDDLE  ALT=\"%28x-%28-3%29%29%5E2+%2B+%28y-1%29%5E2+=+3%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" > Simplify this to:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28x%2B3%29%5E2+%2B+%28y-1%29%5E2+=+9 ALIGN=MIDDLE  ALT=\"%28x%2B3%29%5E2+%2B+%28y-1%29%5E2+=+9\"   DISABLED_style= \"max-width:90%; height:auto;\" >  </SPAN>\n" );
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