document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=980712>Question 980712</A>: <I><SPAN STYLE=\"word-break: break-all;\"> SP)eccentricity of a conic is defined as how the curve deviates from circular shape. i have understood that's why eccentricity of circle is 0. but we know another definition of eccentricity that is ratio of distance between (point on a locus of conic and focus) and between( point on a locus and directrix) therefore if P(x,y) is a point on locus and S the focus and MZ the directrix so, e=SP/PM . FOR a circle focus is the centre of the circle. if i draw a line beside the circle and imagine it as a directrix , therefore apply e=SP/PM , then the ratio is not 0 . so how eccentricity of circle be 0 in last case ? please explain </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #601858 by </B><A HREF=/tutors/aboutme.mpl?userid=macston><B>macston(5194)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=macston><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=macston><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=601858\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .<BR>\n" );
document.write( "Mathematics sort of cheats on this one, and defines the directrix of a circle as \"the line at infinity\", meaning the line is an infinite distance from the circle. Dividing a fixed number (focus to circle, or radius) by infinity is \"approaching zero\". Draw your imaginary directrix an imagined infinity from your circle, and while the ratio e becomes zero for practical purposes, it raises more questions for math theorists to ponder, and may raise questions from you that can be answered more clearly. </SPAN>\n" );
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