document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1185203>Question 1185203</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hi, I hope you are doing fine. Can you help me?\r<BR>\n" );
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document.write( "A skateboard ramp is deigned to have a parabolic cross section. If the ends of the ramp should be 20 feet apart, derived the equation of its cross section using any height of your choice. What is the height of the ramp 5 feet from its center? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #815983 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=815983\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A skateboard ramp is deigned to have a parabolic cross section. If the ends of the ramp should be 20 feet apart, derived the equation of its cross section using any height of your choice. What is the height of the ramp 5 feet from its center?<BR>\n" );
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document.write( "For a parabola centered on the y-axis, y-int = (0,h), and with x-intercepts of -10 and +10:<BR>\n" );
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document.write( "Parabolas have the form y = ax^2 + bx + c<BR>\n" );
document.write( "At x = 0, c = h<BR>\n" );
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document.write( "At x = -10:<BR>\n" );
document.write( "y = a*100 - 10b + h<BR>\n" );
document.write( "At x = +10:<BR>\n" );
document.write( "y = a*100 + 10b + h<BR>\n" );
document.write( "----------------------------------- Subtract<BR>\n" );
document.write( "- 20b = 0<BR>\n" );
document.write( "b = 0<BR>\n" );
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document.write( "Add them<BR>\n" );
document.write( "200a + 2h = 0<BR>\n" );
document.write( "a = -h/100<BR>\n" );
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document.write( "---> y = -hx^2/100 + h<BR>\n" );
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document.write( "5 feet from the center:<BR>\n" );
document.write( "y = -h/4 + h ---> 3h/4<BR>\n" );
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