document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=76195>Question 76195</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0131866710/algebrahomeworkh>College Algebra Essentials</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> Hi, I could really use some help with this. I think I can figure it out if I could just get the quadratic function right, so any help would be appreciated. \r<BR>\n" );
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document.write( "A horizontal bridge is in the shape of a parabolic arch. Given the information shown in the figure (base is 20 ft, height in middle is 10 ft), what is the height h of the arch 2 feet from shore?\r<BR>\n" );
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document.write( "Thank you,<BR>\n" );
document.write( "Jodi </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #54687 by </B><A HREF=/tutors/aboutme.mpl?userid=scott8148><B>scott8148(6628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=scott8148><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=scott8148><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=54687\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> if you picture the bridge sitting on the x-axis and centered on the y-axis, then the parabola passes through (-10,0), (0,10), and (10,0)\r<BR>\n" );
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document.write( "the parabola has the form <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=ax%5E2%2Bbx%2Bc ALIGN=MIDDLE  ALT=\"y=ax%5E2%2Bbx%2Bc\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "substituting (0,10) gives c=10\r<BR>\n" );
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document.write( "substituting (-10,0) gives 0=100a-10b+10\r<BR>\n" );
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document.write( "substituting (10,0) gives 0=100a+10b+10...adding the previous equation gives 0=200a+20...or a=-.1...so b=0\r<BR>\n" );
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document.write( "the equation for the parabola is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=-.1x%5E2%2B10 ALIGN=MIDDLE  ALT=\"y=-.1x%5E2%2B10\"   DISABLED_style= \"max-width:90%; height:auto;\" >...so for x=8(or -8), y=3.6\r<BR>\n" );
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document.write( "you can locate the parabola anywhere and it will change the values of constants, but the answer will be the same </SPAN>\n" );
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