document.write( "Question 1039994: cos(A-B)-sin(A+B)
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Algebra.Com's Answer #654808 by ikleyn(52908)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "cos(A-B) = cos(A)*cos(B) + sin(A)*sin(B),     (1)\r
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\n" ); document.write( "\n" ); document.write( "sin(A+B) = sin(A)*cos(B) + cos(A)*sin(B)      (2)\r
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\n" ); document.write( "\n" ); document.write( "(see any textbook on or including Trigonometry,  or the lesson in this site  Addition and subtraction formulas).
\n" ); document.write( "Taking the difference of  (1)  and  (2),  you get\r
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\n" ); document.write( "\n" ); document.write( "cos(A-B) - sin(A+B) = cos(A)*cos(B) + sin(A)*sin(B) - sin(A)*cos(B) - cos(A)*sin(B) = \r
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\n" ); document.write( "\n" ); document.write( "              = cos(A)*(cos(B)-sin(B)) + sin(A)*(sin(B)-cos(B)) = (cos(A)-sin(A))*(cos(B)-sin(B)).\r
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\n" ); document.write( "\n" ); document.write( "The solution by the other tutor is wrong.\r
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