document.write( "Question 1055398: Find the exact solutions of the equation in the interval [0, 2π). (Enter your answers as a comma-separated list.)
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Algebra.Com's Answer #670624 by ikleyn(52788) $\"\"$ $\"About$

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\n" ); document.write( "Find the exact solutions of the equation in the interval [0, 2π). (Enter your answers as a comma-separated list.)
\n" ); document.write( "cos 2x + cos x = 0
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document.write( "cos(2x) + cos x = 0.\r\n" );
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document.write( "Replace cos(2x) by {{cos^2(x) - sin^2(x)}}} =  = . \r\n" );
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document.write( "Then you get\r\n" );
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document.write( " = 0.\r\n" );
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document.write( "Factor left side:\r\n" );
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document.write( "(2cos(x) - 1)*(cos(x) +1) = 0.\r\n" );
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document.write( "This equation deploys in two independent equations:\r\n" );
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document.write( "1.  2cos(x) - 1 = 0  --->  cos(x) =   --->  x =   and  x =  in the given interval,  and\r\n" );
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document.write( "2.  cos(x) + 1 = 0  --->  cos(x) = -1  --->  x =   in the given interval.\r\n" );
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document.write( "Answer.  The solutions are ,  and .\r\n" );
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\n" ); document.write( "\n" ); document.write( "For many other solved trigonometry equations see the lessons\r
\n" ); document.write( "\n" ); document.write( "    - Solving simple problems on trigonometric equations\r
\n" ); document.write( "\n" ); document.write( "    - Solving typical problems on trigonometric equations\r
\n" ); document.write( "\n" ); document.write( "    - Solving more complicated problems on trigonometric equations\r
\n" ); document.write( "\n" ); document.write( "    - Solving advanced problems on trigonometric equations\r
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