document.write( "Question 1127404: A rhombus has half the area of the square with the same side-length. What is the ratio of the long to short diagonal? \n" ); document.write( "
Algebra.Com's Answer #743894 by ikleyn(52879)\"\" \"About 
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document.write( "Let x be the common length of the square and the rhombus.\r\n" );
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document.write( "Use the formula for the rhombus area \r\n" );
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document.write( "    Rhombus area = \"x%2Ax%2Asin%28alpha%29\" = \"x%5E2%2Asin%28alpha%29\",\r\n" );
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document.write( "where \"alpha\" is the angle between (any) two adjacent sides of the rhombus.\r\n" );
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document.write( "Comparing with the formula for the square area, you can conclude that \"sin%28alpha%29\" = \"1%2F2\";\r\n" );
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document.write( "hence,  the angle   \"alpha\"  is either  30° or 150°, which geometrically represent the same rhombus.\r\n" );
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document.write( "Then the longer diagonal of the rhombus is  ( the law of cosine with cos(150°) = \"-sqrt%283%29%2F2\" )\r\n" );
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document.write( "    \"sqrt%28x%5E2+%2B+x%5E2+-+2%2Ax%2Ax%2Acos%28150%5Eo%29%29\" = \"sqrt%282x%5E2+-+2x%5E2%2A%28-%28sqrt%283%29%2F2%29%29%29\" = \"x%2Asqrt%282%2B2%2A%28sqrt%283%29%2F2%29%29\" = \"x%2Asqrt%282+%2B+sqrt%283%29%29\".\r\n" );
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document.write( "The shorter diagonal is ( the law of cosine with cos(30°) = \"sqrt%283%29%2F2\" )\r\n" );
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document.write( "    \"sqrt%28x%5E2+%2B+x%5E2+-+2%2Ax%2Ax%2Acos%2830%5Eo%29%29\" = \"sqrt%282x%5E2+-+2x%5E2%2A%28sqrt%283%29%2F2%29%29\" = \"x%2Asqrt%282-2%2A%28sqrt%283%29%2F2%29%29\" = \"x%2Asqrt%282+-+sqrt%283%29%29\".\r\n" );
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document.write( "Thus the ratio of the longer diagonal length to the shorter diagonal length is  \"sqrt%282%2Bsqrt%283%29%29%2Fsqrt%282-sqrt%283%29%29\".\r\n" );
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document.write( "You can rationalize this fraction further\r\n" );
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document.write( "    \"sqrt%282%2Bsqrt%283%29%29%2Fsqrt%282-sqrt%283%29%29\" = \"sqrt%282%2Bsqrt%283%29%29%2Fsqrt%282-sqrt%283%29%29\".\"sqrt%282%2Bsqrt%283%29%29%2Fsqrt%282%2Bsqrt%283%29%29\" = \"sqrt%28%282%2Bsqrt%283%29%29%5E2%29%2Fsqrt%282%5E2+-+%28sqrt%283%29%29%5E2%29\" = \"%282%2Bsqrt%283%29%29%2F%284-3%29\" = \"2%2Bsqrt%283%29\" = 3.732 (approximately).\r\n" );
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\n" ); document.write( "\n" ); document.write( "Nice solution to a nice problem.\r
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