document.write( "Question 1109014: A laboratory designed a radio telescope with a diameter of 300 feet and a maximum depth of 44 feet. The graph depicts a cross section of this telescope. Find the equation of this parabola. \n" ); document.write( "
Algebra.Com's Answer #724043 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
A laboratory designed a radio telescope with a diameter of 300 feet and a maximum depth of 44 feet.
\n" ); document.write( " The graph depicts a cross section of this telescope. Find the equation of this parabola
\n" ); document.write( ":
\n" ); document.write( "Using the form y = ax^2 + bx + c, our parabola crosses the origin so c=0
\n" ); document.write( "x = 300 y = 0
\n" ); document.write( "300^2a + 300b = 0
\n" ); document.write( "and
\n" ); document.write( "x = 150, y = 44
\n" ); document.write( "150^2a + 150b = 44
\n" ); document.write( ":
\n" ); document.write( "90000a + 300b = 0
\n" ); document.write( "22500a + 155b = 44
\n" ); document.write( "use elimination, multiply the 2nd equation by 2
\n" ); document.write( "90000a + 300b = 0
\n" ); document.write( "45000a + 300b = 44
\n" ); document.write( "---------------------subtraction eliminates b, find a
\n" ); document.write( "45000a = -44
\n" ); document.write( "a = -44/45000
\n" ); document.write( "a = -.00195
\n" ); document.write( "Find b
\n" ); document.write( "90000(-.001955) + 300b = 0
\n" ); document.write( "-176 + 300b = 0
\n" ); document.write( "300b = 176
\n" ); document.write( "b = 176/300
\n" ); document.write( "b = .5867
\n" ); document.write( "the equation: y = -.00195x^2 + .5867x
\n" ); document.write( "looks like this
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-100%2C+400%2C+-20%2C+100%2C+-.00196x%5E2%2B.5867x%2C+44%29+\"
\n" ); document.write( "green line y = 44, x = 150 \r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
\n" );