document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=858224>Question 858224</A>: <I><SPAN STYLE=\"word-break: break-all;\"> From the top of a vertical cliff 68 metres high, an observer notices a yacht at sea.<BR>\n" );
document.write( "The angle of depression to the yacht is 47 degrees. The yacht sails directly away from the cliff,<BR>\n" );
document.write( "and after 10 minutes the angle of depression is 15 degrees. How fast does the yacht sail? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #517113 by </B><A HREF=/tutors/aboutme.mpl?userid=mananth><B>mananth(16946)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mananth><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=mananth><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=517113\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> height of tower = 68m\r<BR>\n" );
document.write( "\n" );
document.write( "angle of depression = 47 deg\r<BR>\n" );
document.write( "\n" );
document.write( "angle of depression after 10 minutes  = 15 deg\r<BR>\n" );
document.write( "\n" );
document.write( "10 min = 600 seconds\r<BR>\n" );
document.write( "\n" );
document.write( "Let the initial ground distance from tower to yacht x m\r<BR>\n" );
document.write( "\n" );
document.write( "Tan 47 = 68/x<BR>\n" );
document.write( "x= 68/tan 47\r<BR>\n" );
document.write( "\n" );
document.write( "Let the speed of the yacht = y\r<BR>\n" );
document.write( "\n" );
document.write( "distance traveled in 600 seconds = 600y\r<BR>\n" );
document.write( "\n" );
document.write( "Tan 15 = 68/(x+600y) \r<BR>\n" );
document.write( "\n" );
document.write( "x+600y = 68/tan 15\r<BR>\n" );
document.write( "\n" );
document.write( "x= (68/tan 15)-600y\r<BR>\n" );
document.write( "\n" );
document.write( "68/tan47 = (68/tan 15)-600y\r<BR>\n" );
document.write( "\n" );
document.write( "600y = (68/tan 15)- (68/tan 47)\r<BR>\n" );
document.write( "\n" );
document.write( "600y=253.8-63.4\r<BR>\n" );
document.write( "\n" );
document.write( "y=0.32 m/s------ speed of the yacht </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );