document.write( "Question 305319: if a+b=90degree, then the maximum value of cosacosb is.. \n" ); document.write( "
Algebra.Com's Answer #218579 by Edwin McCravy(20056)\"\" \"About 
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if a+b=90degree, then the maximum value of cosacosb is..
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document.write( "Let a = x, since the letters x is usually a variable, and \r\n" );
document.write( "letters a and b are usually constants.  Then b = 90°-a = 90°-x \r\n" );
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document.write( "I will approach it from a calculus standpoint.\r\n" );
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document.write( "y = cos(x)cos(90-x)\r\n" );
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document.write( "y = cos(x)sin(x)\r\n" );
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document.write( "\"%28dy%29%2F%28dx%29+=+Cos%282x%29\"\r\n" );
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document.write( "Setting that = 0\r\n" );
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document.write( "Cos(2x)=0\r\n" );
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document.write( "2x = 90°, 270°, 450°, etc.\r\n" );
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document.write( "x = 45°, 135°, 225°, etc.\r\n" );
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document.write( "Substituting these in \r\n" );
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document.write( "y = cos(x)sin(x)\r\n" );
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document.write( "y = cos(45°)sin(45°) = \"%28sqrt%282%29%2F2%29%2A%28sqrt%282%29%2F2%29=2%2F4+=+1%2F2\"\r\n" );
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document.write( "y = cos(135°)sin(135°) = \"%28-sqrt%282%29%2F2%29%2A%28sqrt%282%29%2F2%29=-2%2F4+=+-1%2F2\"\r\n" );
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document.write( "y = cos(225°)sin(225°) = \"%28-sqrt%282%29%2F2%29%2A%28-sqrt%282%29%2F2%29=2%2F4+=+1%2F2\"\r\n" );
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document.write( "etc.\r\n" );
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document.write( "So the maximum value is \"1%2F2\" and the minimum value is \"-1%2F2\".\r\n" );
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document.write( "Edwin
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