document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1191911>Question 1191911</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A circular ripple spreads across a lake. If the area of the ripple increases <BR>\n" );
document.write( "at a rate of 10pi m^2s^-1,<BR>\n" );
document.write( "find the rate at which the radius is increasing when the radius is 2 m. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #823779 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52803)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=823779\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .\r<BR>\n" );
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document.write( "Physically, when a stone is dropped into a still pond sending out a circular ripple of the radius r = r(t), \r<BR>\n" );
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document.write( "the rate  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28dr%29%2F%28dt%29 ALIGN=MIDDLE  ALT=\"%28dr%29%2F%28dt%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >  is constant and is equal to the speed of surface wave.\r<BR>\n" );
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document.write( "The area of the circle is a quadratic function of time, in this case.\r<BR>\n" );
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document.write( "So, in reality, the radius r= r(t) and the area A = A(t) are different types of functions, distinct of described in this problem.\r<BR>\n" );
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document.write( "You may find many Internet sources, related to this phenomenon.\r<BR>\n" );
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