document.write( "Question 1085650: verify the identity of sin(x+y) + sin (x-y) = 2sin x cos y \n" ); document.write( "
Algebra.Com's Answer #699709 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "Use the following sum and difference identities to confirm the identity
\n" ); document.write( "sin(x+y) = sin(x)cos(y) + cos(x)sin(y)
\n" ); document.write( "sin(x-y) = sin(x)cos(y) - cos(x)sin(y)\r
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\n" ); document.write( "\n" ); document.write( "Only alter the left side\r
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\n" ); document.write( "\n" ); document.write( "sin(x+y) + sin(x-y) = 2*sin(x)*cos(y)
\n" ); document.write( "sin(x+y) + sin (x-y) = 2*sin(x)*cos(y)
\n" ); document.write( "sin(x)cos(y) + cos(x)sin(y) + sin (x-y) = 2*sin(x)*cos(y)
\n" ); document.write( "sin(x)cos(y) + cos(x)sin(y) + sin(x-y) = 2*sin(x)*cos(y)
\n" ); document.write( "sin(x)cos(y) + cos(x)sin(y) + sin(x)cos(y) - cos(x)sin(y) = 2*sin(x)*cos(y)
\n" ); document.write( "sin(x)cos(y) + cos(x)sin(y) + sin(x)cos(y) - cos(x)sin(y) = 2*sin(x)*cos(y)
\n" ); document.write( "[sin(x)cos(y) + sin(x)cos(y)] + [cos(x)sin(y) - cos(x)sin(y)] = 2*sin(x)*cos(y)
\n" ); document.write( "[2*sin(x)*cos(y)] + [0*cos(x)sin(y)] = 2*sin(x)*cos(y)
\n" ); document.write( "2*sin(x)*cos(y) = 2*sin(x)*cos(y)\r
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\n" ); document.write( "\n" ); document.write( "The identity has been confirmed.
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