document.write( "Question 1007358: For cos(x)cos(3x)-sin(x)sin(3x)=0, use an addition or subtraction formula to simplify the equation and then find all solutions of the equation in the interval [0,pi)\r
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\n" ); document.write( "\n" ); document.write( "cos(x)cos(3x)-sin(x)sin(3x)=0\r
\n" ); document.write( "\n" ); document.write( "cos(x+3x)=cos(x)cos(3x)-sin(x)sin(3x)
\n" ); document.write( " =3x^2-3x^2
\n" ); document.write( "i'm stuck about on this part because I cannot find x1,x2,x3,x4 with x1 < x2 < x3 < x4
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Algebra.Com's Answer #623339 by ikleyn(52821) $\"\"$ $\"About$

You can put this solution on YOUR website!
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document.write( "Do you know this formula \r\n" );
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document.write( " =  ?\r\n" );
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document.write( "It is standard formula of Trigonometry. It can be found in any textbook in Trigonometry. \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( "Use it, and your life will be much easier.\r\n" );
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