document.write( "Question 1043276: Solve the equation for exact solutions over the interval [0, 2π).\r
\n" ); document.write( "\n" ); document.write( "cos2x + 2 cos x + 1 = 0 \n" ); document.write( "
Algebra.Com's Answer #658412 by ikleyn(52786)\"\" \"About 
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\n" ); document.write( "Solve the equation for exact solutions over the interval [0, 2π).\r
\n" ); document.write( "\n" ); document.write( "cos2x + 2 cos x + 1 = 0
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document.write( "\"cos%5E2%28x%29+%2B+2cos%28x%29+%2B+1\" = \"0\",  --->  ( apply the formula \"a%5E2+%2B+2a+%2B+1\" = \"%28a%2B1%29%5E2\" )  --->\r\n" );
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document.write( "\"%28cos%28x%29%2B1%29%5E2\" = \"0\",  --->\r\n" );
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document.write( "cos(x) + 1 = 0  --->\r\n" );
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document.write( "cos(x) = -1  --->\r\n" );
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document.write( "x = \"pi\".\r\n" );
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document.write( "Answer.  x = \"pi\".\r\n" );
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\n" ); document.write( "\n" ); document.write( "Or, if your original equation is \"cos%282x%29+%2B+cos%28x%29+%2B+1\" = \"0\", \r
\n" ); document.write( "\n" ); document.write( "then see the solution under this link\r
\n" ); document.write( "\n" ); document.write( "https://www.algebra.com/algebra/homework/Trigonometry-basics/Trigonometry-basics.faq.question.906637.html\r
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\n" ); document.write( "\n" ); document.write( "https://www.algebra.com/algebra/homework/Trigonometry-basics/Trigonometry-basics.faq.question.906637.html\r
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