document.write( "Question 999931: A wire, 130 cm long, is cut into two pieces. One piece is bent to form a square of side x cm and the other piece is bent to form a circle of radius r cm. The total area of the square and the circle is A cm^2.\r
\n" ); document.write( "\n" ); document.write( "(a) show that A= \"%28%28%28%26%23960%3B%2B4%29x%B2%29+-+%28260x%29+%2B+4225%29%2F+%26%23960%3B\"\r
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\n" ); document.write( "\n" ); document.write( "if the formula plot doesn't work, this is the formula:
\n" ); document.write( " (((π+4)x²) - (260x) + 4225)/ π\r
\n" ); document.write( "\n" ); document.write( "(b) given that x and r can vary, find the value of x for which a has a stationary value\r
\n" ); document.write( "\n" ); document.write( "thanks in advance
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Algebra.Com's Answer #617497 by Fombitz(32388)\"\" \"About 
You can put this solution on YOUR website!
The contribution of length from the square is \"L%5B1%5D=4x\".
\n" ); document.write( "The contribution of length from the circle is \"L%5B2%5D=2pi%2Ar\"
\n" ); document.write( "\"L%5B1%5D%2BL%5B2%5D=130\"
\n" ); document.write( "\"4x%2B2pi%2Ar=130\"
\n" ); document.write( "\"2x%2Bpi%2Ar=65\"
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\n" ); document.write( "For the square,
\n" ); document.write( "\"A%5Bs%5D=x%5E2\"
\n" ); document.write( "For the circle,
\n" ); document.write( "\"A%5Bc%5D=pi%2Ar%5E2\"
\n" ); document.write( "So then,
\n" ); document.write( "\"A=A%5Bs%5D%2BA%5Bc%5D\"
\n" ); document.write( "\"A=x%5E2%2Bpi%2Ar%5E2\"
\n" ); document.write( "From the length above,
\n" ); document.write( "\"pi%2Ar=65-2x\"
\n" ); document.write( "\"r=%2865-2x%29%2Fpi\"
\n" ); document.write( "\"pi%5E2r%5E2=%2865-2x%29%5E2\"
\n" ); document.write( "\"pi%5E2r%5E2=4x%5E2-260x%2B4225\"
\n" ); document.write( "\"pi%2Ar%5E2=%284x%5E2-260x%2B4225%29%2Fpi\"
\n" ); document.write( "Substituting into the area formula,
\n" ); document.write( "\"A=x%5E2%2B%284x%5E2-260x%2B4225%29%2Fpi\"
\n" ); document.write( "\"A=%28pi%2Ax%5E2%29%2Fpi%2B%284x%5E2-260x%2B4225%29%2Fpi\"
\n" ); document.write( "\"A=%28%284%2Bpi%29x%5E2-260x%2B4225%29%2Fpi\"
\n" ); document.write( ".
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\n" ); document.write( "Stationary value is where the derivative of A with respect to x equals zero.
\n" ); document.write( "\"2%284%2Bpi%29x-260=0\"
\n" ); document.write( "\"x=260%2F%282%284%2Bpi%29%29\"
\n" ); document.write( "\"x=130%2F%284%2Bpi%29\"\r
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