(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

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2. Relevant equations

3. The attempt at a solution

y = tanx^cosx

lny = cosx(ln(tanx))

1/y(dy/dx) = (sec^2x * cosx)/tanx + ln(tanx)(-sinx)

at pi/4

1/y(dy/dx) = (1 * 1/sqrt(2))/1 + ln(1)(-sin(pi/4))

1/y(dy/dx) = 1/sqrt(2) + 0 ******* ln1 = 0

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y = tanx^cosx => 1^(1/sqrt(2)) = 1 => 1/y = 1

***

dy/dx at pi/4 = 1/sqrt(2)

The answer is sqrt(2) NOT 1/sqrt(2)

What am I doing wrong?

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# Homework Help: Value of the differential of tan(x)^cos(x) at pi/4

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