document.write( "Question 1106544: A close cylindrical tank 10ft in height and 4ft in diameter contains water with depth of 3ft and 5 inches. What would be the height of the water when the tank is lying in a horrizontal position? \n" ); document.write( "
Algebra.Com's Answer #721596 by ikleyn(52787)\"\" \"About 
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\n" ); document.write( "A close cylindrical tank 10ft in height and 4ft in diameter contains water with depth of 3ft and 5 inches.
\n" ); document.write( "What would be the height of the water when the tank is lying in a horrizontal position?
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document.write( "First, convert dimensions from feet to inches:  H = 10 ft = 120 in,  h = 3 feet 5 inches = 12*3+5 = 41 in,  r = 2 ft = 24 inches.\r\n" );
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document.write( "The volume of the tank is  V = \"pi%2Ar%5E2%2AH\" = \"pi%2Ar%5E2%2A120\" = \"120pi%2Ar%5E2\".\r\n" );
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document.write( "The filled volume of the tank is  F = \"pi%2Ar%5E2%2Ah\" = \"41pi%2Ar%5E2\".\r\n" );
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document.write( "The ratio of the filled part to the total volume is  \"F%2FV\" = \"41%2F120\".\r\n" );
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document.write( "In any position (vertical/horizontal) the filled part is  \"41%2F120\" of the total volume.\r\n" );
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document.write( "Hence, we need to find the central angle of the circle which subtends the segment of the circle whose area is \"41%2F120\" of the circle area.\r\n" );
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document.write( "The area of the segment of a circle is  A = \"%281%2F2%29%2Ar%5E2%2Aalpha+-+%281%2F2%29%2Ar%5E2%2Asin%28alpha%29\",  where \"alpha\" is the central angle in radians.\r\n" );
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document.write( "Hence, we need to solve the equation\r\n" );
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document.write( "\"%281%2F2%29%2Ar%5E2%2Aalpha+-+%281%2F2%29%2Ar%5E2%2Asin%28alpha%29\" = \"%2841%2F120%29%2Api%2Ar%5E2\",\r\n" );
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document.write( "or, canceling r^2 in both sides\r\n" );
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document.write( "\"%281%2F2%29%2Aalpha+-+%281%2F2%29%2Asin%28alpha%29\" = \"%2841%2Api%2F120%29\" = 1.07283.\r\n" );
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document.write( "I solved this non-linear equation using Excel function  \"Goal Seek\" of  the section \"What-if\"  in my computer.\r\n" );
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document.write( "The answer is \"alpha\" = 2.633 radians.\r\n" );
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document.write( "Since the problem asks about the depth, it is  \"r-r%2Acos%28alpha%2F2%29\" = \"24-24%2Ac0s%282.633%2F2%29\" = 17.96 inches.     (24 = 24 inches = r = 2 ft is the radius)\r\n" );
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\n" ); document.write( "\n" ); document.write( "Answer. The depth under the question is 17.96 inches.\r
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