document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=299600>Question 299600</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The equation of the inner circle is x2 + y2 = 9. The radius of the outer circle is three times the radius of the inner circle. What is the equation of the outer circle </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #215221 by </B><A HREF=/tutors/aboutme.mpl?userid=dabanfield><B>dabanfield(803)</B></A><img src=\"/images/stars/stars-11.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=dabanfield><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=215221\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The equation of the inner circle is x2 + y2 = 9. The radius of the outer circle is three times the radius of the inner circle. What is the equation of the outer circle\r<BR>\n" );
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document.write( "The standard form of a circle with center at (h,k) and radius r is:\r<BR>\n" );
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document.write( "(x-h)^2 + (y-k)^2 = r^2\r<BR>\n" );
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document.write( "The inner circle's equation can be rewritten as:\r<BR>\n" );
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document.write( "(x-0)^2 + (y-0)^2 = 3^2 and so has center at (0,0) and radius 3.\r<BR>\n" );
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document.write( "Since the outer circle also has center at (0,0) but has radius 3*3 = 9 its equation is:\r<BR>\n" );
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document.write( "(x-0)^2 + (y-0)^2 = 9^2 or\r<BR>\n" );
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document.write( "x^2 + y^2 = 81 </SPAN>\n" );
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