document.write( "Question 27798: Differentitate\r
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\n" ); document.write( "\n" ); document.write( "y=cosxsinx\r
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\n" ); document.write( "\n" ); document.write( "I tried doing it by the product rule but it didn't work.
\n" ); document.write( "thanks. \n" ); document.write( "
Algebra.Com's Answer #15137 by sdmmadam@yahoo.com(530)\"\" \"About 
You can put this solution on YOUR website!
Differentitate y=cosxsinx
\n" ); document.write( "y=cosxsinx
\n" ); document.write( "(dy/dx) = (cosx)[d/dx of (sinx)] + (sinx)[d/dx of (cosx)]
\n" ); document.write( "(using the product rule:
\n" ); document.write( "(first X derivative of the second)+ (second X derivative of the first)
\n" ); document.write( "=(cosx)X(cosx) + (sinx)X(-sinx)
\n" ); document.write( "= (cosx)^2 -(sinx)^2
\n" ); document.write( "= cos(2x) by formula
\n" ); document.write( "Another method:
\n" ); document.write( "y=cosxsinx = (1/2)(2sinxcosx) = (1/2)sin(2x)
\n" ); document.write( "(dy/dx) = (1/2)[d/dx of (sin2x)]
\n" ); document.write( "using (derivative of a constant times funciton
\n" ); document.write( "= constant times derivativeof the function)
\n" ); document.write( "= (1/2)(cos(2x))X[d/dx of (2x)] by chain rule
\n" ); document.write( "= (1/2)(cos(2x))X2
\n" ); document.write( "= cos(2x) \n" ); document.write( "
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