Posted by sh on Sunday, March 21, 2010 at 11:02pm.
Find the derivative of y with respect to x:
y=(1+cos²x)^6
y'=6(1+cos²x)^5
How do you derive inside the brackets? The answer says sin2x, but wouldn't it be 2sinx, using the chain rule.

Calculus  Reiny, Sunday, March 21, 2010 at 11:06pm
You still have to differentiate the "inside"
d(1+cos^2x) = 2cosx(sinx)
= 2sinxcox
= sin 2x, one of the identities
so
y'=6(1+cos²x)^5(sin2x)
= y'= 6(1+cos²x)^5(sin2x)

Calculus  sh, Sunday, March 21, 2010 at 11:30pm
Oh, I see it now, thanks!
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