document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=709993>Question 709993</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Write an equation for a circle if the endpoints of a diameter are at (-2,-1) and (8,9)? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #437000 by </B><A HREF=/tutors/aboutme.mpl?userid=lwsshak3><B>lwsshak3(11628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=lwsshak3><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=437000\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Write an equation for a circle if the endpoints of a diameter are at (-2,-1) and (8,9)<BR>\n" );
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document.write( "center of circle=midpoint of diameter endpoints.<BR>\n" );
document.write( "midpoint: [(x1+x2)/2),(y1+y2)/2]<BR>\n" );
document.write( "=[(-2+8)/2, (-1+9)/2]<BR>\n" );
document.write( "=(3,4)<BR>\n" );
document.write( "Equation of circle: (x-h)^2+(y-k)^2=r^2, (h,k)=(x,y) coordinates of center, r=radius<BR>\n" );
document.write( "Find radius using one of the points on the circle (-2,-1)<BR>\n" );
document.write( "(-2-3)^2+(-1-4)^2=r^2<BR>\n" );
document.write( "25+25=r^2<BR>\n" );
document.write( "r^2=50<BR>\n" );
document.write( "equation of circle: (x-3)^2+(y-4)^2=50 </SPAN>\n" );
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