document.write( "Question 1030520: Find all solutions in the interval [0, 2π). cosθcos2θ+sinθsin2θ= sqrt2/2
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Algebra.Com's Answer #645446 by ikleyn(52788) $\"\"$ $\"About$

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document.write( "Use the formula   = \r\n" );
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document.write( "(see, for example, the lesson Addition and subtraction formulas in this site).\r\n" );
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document.write( "It gives you \r\n" );
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document.write( " =  = .\r\n" );
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document.write( "So, your original equation becomes\r\n" );
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document.write( " = .   (1)\r\n" );
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document.write( "Since    is always equal to  , you can rewrite (1) in the form\r\n" );
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document.write( " = .   (2)\r\n" );
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document.write( "The equation (2) has two and only two solutions in the given interval.\r\n" );
document.write( "They are   =   and/or   = .\r\n" );
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