document.write( "Question 1041677: a window has the form of a rectangle surrounded by a semi circle if perimeter is 40 units.find its dimensions so that the area of window is maximum \n" ); document.write( "
Algebra.Com's Answer #656643 by Fombitz(32388)\"\" \"About 
You can put this solution on YOUR website!
Assume the window is X wide and Y long.
\n" ); document.write( "So then the perimeter of the window would be.
\n" ); document.write( "\"P=X%2B2Y%2B%28pi%2F2%29%2AX\"
\n" ); document.write( "1.\"%281%2Bpi%2F2%29X%2B2Y=40\"
\n" ); document.write( "and the area of the window would be,
\n" ); document.write( "\"A=XY%2B%28pi%2F2%29%28X%2F2%29%5E2\"
\n" ); document.write( "2.\"A=XY%2B%28pi%2F8%29X%5E2\"
\n" ); document.write( "From eq. 1,
\n" ); document.write( "\"2Y=40-%281%2Bpi%2F2%29X\"
\n" ); document.write( "\"Y=20-%28%281%2Bpi%2F2%29%2F2%29X\"
\n" ); document.write( "\"Y=20-%281%2F2%2Bpi%2F4%29X\"
\n" ); document.write( "Let's just call the constant in front of X, B, just for better readability.
\n" ); document.write( "\"Y=20-BX\"
\n" ); document.write( "So then substituting into 2,
\n" ); document.write( "\"A=X%2820-BX%29%2B%28pi%2F8%29X%5E2\"
\n" ); document.write( "\"A=20X-BX%5E2%2B%28pi%2F8%29X%5E2\"
\n" ); document.write( "\"A=%28pi%2F8-B%29X%5E2%2B20X\"
\n" ); document.write( "\"A=%28pi%2F8-1%2F2-pi%2F4%29X%5E2%2B20X\"
\n" ); document.write( "\"A=%28-pi%2F8-1%2F2%29X%5E2%2B20X\"
\n" ); document.write( "\"A=-%28%284%2Bpi%29%2F8%29X%5E2%2B20X\"
\n" ); document.write( "Once again, let's use a constant, C.
\n" ); document.write( "\"A=CX%5E2%2B20X\"
\n" ); document.write( "Convert to vertex form to find the vertex and maximum area.
\n" ); document.write( "\"A=C%28X%5E2%2B%2820%2FC%29X%29\"
\n" ); document.write( "\"A=C%28X%5E2%2B%2820%2FC%29X%2B%2810%2FC%29%5E2%29-C%2810%2FC%29%5E2\"
\n" ); document.write( "\"A=C%28X%2B10%2FC%29%5E2-100%2FC\"
\n" ); document.write( "\"A=-%28%284%2Bpi%29%2F8%29%28X-80%2F%284%2Bpi%29%29%2B800%2F%284%2Bpi%29\"
\n" ); document.write( "So the maximum area of
\n" ); document.write( "\"A%5Bmax%5D=800%2F%284%2Bpi%29\"
\n" ); document.write( "occurs when,
\n" ); document.write( "\"highlight%28X=80%2F%284%2Bpi%29%29\"
\n" ); document.write( "and
\n" ); document.write( "\"Y=20-%281%2F2%2Bpi%2F4%29%2880%2F%284%2Bpi%29%29\"\r
\n" ); document.write( "\n" ); document.write( "\"Y=20-%28%282%2Bpi%29%2F4%29%2880%2F%284%2Bpi%29%29\"
\n" ); document.write( "\"Y=20-%28%282%2Bpi%29%2F%284%2Bpi%29%29%2A20\"
\n" ); document.write( "\"Y=20%281-%282%2Bpi%29%2F%284%2Bpi%29%29\"
\n" ); document.write( "\"Y=20%28%284%2Bpi%29%2F%284%2Bpi%29-%282%2Bpi%29%2F%284%2Bpi%29%29\"
\n" ); document.write( "\"Y=20%28%284%2Bpi-2-pi%29%2F%284%2Bpi%29%29\"
\n" ); document.write( "\"Y=20%282%2F%284%2Bpi%29%29\"
\n" ); document.write( "\"highlight%28Y=40%2F%284%2Bpi%29%29\"
\n" ); document.write( "
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