Posted by calculus on Thursday, September 19, 2013 at 11:49am.
if y=cosx.sinx find dy/dx

calculus  Steve, Thursday, September 19, 2013 at 11:53am
just use the product rule
If y = fg, then
y' = f'g + fg'
So,
dy.dx = sinx.sinx + cosx.cosx
= cos^2x  sin^2x
= cos2x
Or, you could have noticed that
y = 1/2 sin2x, so
y' = cos2x
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