document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1185542>Question 1185542</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The cables of a suspension bridge are in the shape of a parabola. The towers supporting the cable are 600 feet and 80 feet high, with the cables touching the road surface midway between the towers.<BR>\n" );
document.write( "a.) Find the equation of the shape of the cable<BR>\n" );
document.write( "b.) What is the height of the cable from the road at a point 150 ft from the center of the bridge<BR>\n" );
document.write( "c.) Using the equation from part a, determine the total length of cable needed for the vertical sections of the cables spaced 20-foot interval. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #816361 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=816361\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A similar problem:<BR>\n" );
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document.write( "A cable suspended between two posts that are the same height and 20 meters apart has a sag of 1 1/2 meter. If the cable hangs in the form of a parabola, find its equation, taking the lowest point as the origin.<BR>\n" );
document.write( "---------------------<BR>\n" );
document.write( "3 points on the parabola are:<BR>\n" );
document.write( "(-10,1.5), (0,0), (10,1.5)<BR>\n" );
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document.write( "A parabola has the form y = ax^2 + bx + c<BR>\n" );
document.write( "Sub the values and solve for a, b & c.<BR>\n" );
document.write( "Do the (0,0) first:<BR>\n" );
document.write( "0 = a*0 + b*0 + c ---> c = 0<BR>\n" );
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document.write( "For (-10,1.5):<BR>\n" );
document.write( "1.5 = a*100 - 10b<BR>\n" );
document.write( "For (10,1.5):<BR>\n" );
document.write( "1.5 = a*100 + 10b<BR>\n" );
document.write( "1.5 = a*100 - 10b<BR>\n" );
document.write( "--------------------- Subtract<BR>\n" );
document.write( "0 = 20b<BR>\n" );
document.write( "b = 0<BR>\n" );
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document.write( "1.5 = a*100 + 10b<BR>\n" );
document.write( "1.5 = a*100 - 10b<BR>\n" );
document.write( "-----------------------Add<BR>\n" );
document.write( "3 = 200a<BR>\n" );
document.write( "a = 3/200<BR>\n" );
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document.write( "y = (3/200)x^2 is the parabola<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );