document.write( "Question 675817: A Norman Window is a rectangle with a semi-circle on top of it. Big Sky Window is designing a Norman window that will require 8m of trim around the perimeter of the window. What dimensions will allow the maximum amount of light to enter a house? \n" ); document.write( "
Algebra.Com's Answer #420223 by ankor@dixie-net.com(22740)\"\" \"About 
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A Norman Window is a rectangle with a semi-circle on top of it.
\n" ); document.write( "Big Sky Window is designing a Norman window that will require 8m of trim around the perimeter of the window.
\n" ); document.write( "What dimensions will allow the maximum amount of light to enter a house?
\n" ); document.write( ":
\n" ); document.write( "This can be summed up in the statement:
\n" ); document.write( "\"Find the max area for a perimeter of 8 meters\"
\n" ); document.write( ":
\n" ); document.write( "Let W = the width of the rectangular portion and the diameter of semi-circle
\n" ); document.write( ".5W = the radius of the semicircle
\n" ); document.write( "let L = the length of the rectangular portion (height of the window)
\n" ); document.write( ":
\n" ); document.write( "Perimeter
\n" ); document.write( "2 vert lengths + 1 lower width + half the circumference
\n" ); document.write( "2L + W + .5W*pi = 8
\n" ); document.write( "2L + W + 1.57W = 8
\n" ); document.write( "2L + 2.57W = 8
\n" ); document.write( "Divide by 2
\n" ); document.write( "L + 1.285W = 4
\n" ); document.write( "L = (4-1.285W)
\n" ); document.write( ":
\n" ); document.write( "Area
\n" ); document.write( "A = L*W + [.5*pi*(.5W)^2]
\n" ); document.write( "A = L*W + [.5*pi*.25W^2
\n" ); document.write( "A = L*W + .3927W^2
\n" ); document.write( "Replace L with (4-1.285W)
\n" ); document.write( "A = W(4-1.285W) + .3927W^2
\n" ); document.write( "A = 4W-1.285W^2 + .3927W^2
\n" ); document.write( "A quadratic equation
\n" ); document.write( "A = -.8923W^2 + 4W
\n" ); document.write( "Find the axis of symmetry
\n" ); document.write( "W = -4/2(-.8923)
\n" ); document.write( "W = -4/-1.7846
\n" ); document.write( "W = 2.24 meters is the width of the window for max area
\n" ); document.write( "Find L
\n" ); document.write( "L = 4 - 1.285(2.24)
\n" ); document.write( "L = 4 - 2.8784
\n" ); document.write( "L = 1.12 meters is the height of the window for max area
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check this by finding the perimeter
\n" ); document.write( "p = 2(1.12 + 2.24 +(.5*pi*2.24)
\n" ); document.write( "p = 2.24 + 2.24 + 3.52
\n" ); document.write( "p = 8 meters
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