document.write( "Question 37163: this question is not out of the book...\r
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document.write( "Find what the minimum surface area for a cylindrical can will be to hold . Give the radius and the height.\r
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Algebra.Com's Answer #22848 by fractalier(6550)![]() ![]() You can put this solution on YOUR website! Since we wish to minimize surface area, we will need to find r when dA/dr = 0.\r \n" ); document.write( "\n" ); document.write( "(1) A = 2(pi)r^2 + 2(pi)rh\r \n" ); document.write( "\n" ); document.write( "We can find h in terms of r by considering the volume formula\r \n" ); document.write( "\n" ); document.write( "V = (pi)r^2h\r \n" ); document.write( "\n" ); document.write( "500 = (pi)r^2h\r \n" ); document.write( "\n" ); document.write( "h = 500/(pi)r^2\r \n" ); document.write( "\n" ); document.write( "Substituting into (1) above, we get\r \n" ); document.write( "\n" ); document.write( "A = 2(pi)r^2 + 2(pi)r(500/(pi)r^2)\r \n" ); document.write( "\n" ); document.write( "A = 2(pi)r^2 + 1000/r\r \n" ); document.write( "\n" ); document.write( "Now take dA/dr and set it equal to zero.\r \n" ); document.write( "\n" ); document.write( "dA/dr = 4(pi)r - 1000/r^2 = 0\r \n" ); document.write( "\n" ); document.write( "And r = cube root of (250/pi)\r \n" ); document.write( "\n" ); document.write( "From there you can find h and A. \n" ); document.write( " |