document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=980071>Question 980071</A>: <I><SPAN STYLE=\"word-break: break-all;\"> What is the rectangular form of the equation r= -16cos(theta)? The answer choices are: A.(x+8)^2+y^2=64 B. x^2+(y-8)^2=64 and C. (x-8)^2+y^2=64  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #601287 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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=601287\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Identities Used\r<BR>\n" );
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document.write( "r^2 = x^2 + y^2<BR>\n" );
document.write( "x = r*cos(theta)\r<BR>\n" );
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document.write( "-------------------------------------------------------\r<BR>\n" );
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document.write( "r= -16cos(theta)\r<BR>\n" );
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document.write( "r*r= r*(-16cos(theta)) ... multiply both sides by r\r<BR>\n" );
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document.write( "r^2 = -16(rcos(theta))\r<BR>\n" );
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document.write( "r^2 = -16x ... replace \"rcos(theta)\" with x (see above)\r<BR>\n" );
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document.write( "x^2 + y^2 = -16x ... replace r^2 with x^2+y^2 (see above)\r<BR>\n" );
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document.write( "x^2+16x + y^2 = 0\r<BR>\n" );
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document.write( "x^2+16x +64 + y^2 = 0+64 ... see note below\r<BR>\n" );
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document.write( "(x^2+16x +64) + y^2 = 64\r<BR>\n" );
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document.write( "(x+8)^2 + y^2 = 64\r<BR>\n" );
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document.write( "This is a circle with center (-8,0) and radius 8\r<BR>\n" );
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document.write( "Note: I took half of the x coefficient (16) to get 8. Then I squared 8 to get 64. I added 64 to both sides. This is all done to complete the square.  </SPAN>\n" );
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