document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1052889>Question 1052889</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A laboratory designed a radio telescope with a diameter of 380 feet and a maximum depth of 42 feet. The graph depicts a cross section of this telescope. Find the equation of this parabola. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #668180 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=668180\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  A laboratory designed a radio telescope with a diameter of 380 feet and a maximum depth of 42 feet. The graph depicts a cross section of this telescope. Find the equation of this parabola. <BR>\n" );
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document.write( "Points of the parabola:: (-190,0),(0,-42),(190,0)<BR>\n" );
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document.write( "Form:: ax^2 + bx + c = y<BR>\n" );
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document.write( "Using (0,-42) you get c = -42<BR>\n" );
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document.write( "Using (-190,0):: 190^2a - 190b = +42<BR>\n" );
document.write( "Using (190,0) :: 190^2a + 190b = 42<BR>\n" );
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document.write( "2(190^2a) = 84<BR>\n" );
document.write( "a = 0.0012<BR>\n" );
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document.write( "Solve for \"b\"::<BR>\n" );
document.write( "190b = 42 - 190^2*0012<BR>\n" );
document.write( "190b = -1.32<BR>\n" );
document.write( "b = -0.0069<BR>\n" );
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document.write( "Equation:<BR>\n" );
document.write( "y = 0.0012x^2 - 0.0069x -42 = 0<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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