Derivative of cos(e^-θ^2) using the chain rule | Power and exponential rules

In summary, to find the derivative of cos(e^-θ^2), we first use the chain rule by letting u = e^-θ^2. Then, we use the power rule to find the derivative of u, which is du = -2θe^-θ^2 dθ. Finally, we substitute these values into the derivative formula for cos(u), giving us -sin(e^-θ^2) * -2θe^-θ^2, or 2θsin(e^-θ^2) * e^-2θ.
  • #1
jaydnul
558
15

Homework Statement


Find the derivative of the following

cos(e^-θ^2)


Homework Equations


cos=-sin
e^x=e^x
power rule


The Attempt at a Solution


So I have gotten this far: -sin(e^-θ^2) * ... but then i don't know where to go. Would I treat the -θ^2 as the next step inwards? My best guess would be this:

-sin(e^-θ^2) * e^-2θ * e^-θ^2
 
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  • #2
This is chain rule inside of the chain rule.

So, [tex]{\cos(e^{-θ^2})}[/tex] let [tex]u=e^{-θ^2}[/tex] to find du, let[tex]v=-θ^2[/tex][tex]dv=-2θd{\theta}[/tex] so [tex]du=-2θe^{-θ^2}d{\theta}[/tex] and finally [tex]{\frac{d({cos(u)})}{du}=-{sin(u)}du}[/tex]
 
Last edited:
  • #3
Perfect
 

1. What is the chain rule?

The chain rule is a rule in calculus that allows you to find the derivative of a composite function. It states that the derivative of a composition of two functions is equal to the derivative of the outer function evaluated at the inner function, multiplied by the derivative of the inner function.

2. How do you apply the power rule in this scenario?

In this scenario, we can apply the power rule by first rewriting the function as cos(e^(-θ^2)) and then using the fact that the derivative of cos(x) is -sin(x). This gives us -sin(e^(-θ^2)).

3. Can you provide a step-by-step explanation for finding the derivative using the chain rule?

Step 1: Rewrite the function as cos(e^(-θ^2)).
Step 2: Identify the inner function, in this case e^(-θ^2).
Step 3: Find the derivative of the outer function, which is -sin(x).
Step 4: Find the derivative of the inner function, which is -2θe^(-θ^2).
Step 5: Multiply the two derivatives together, giving us -sin(e^(-θ^2)) * -2θe^(-θ^2).
Step 6: Simplify the expression to get the final answer of 2θsin(e^(-θ^2)).

4. Are there any other rules that need to be applied in this scenario?

In addition to the power rule and the chain rule, we also need to apply the exponential rule when finding the derivative of e^(-θ^2). This rule states that the derivative of e^x is e^x, so the derivative of e^(-θ^2) is -2θe^(-θ^2).

5. Can the chain rule be applied to any composite function?

Yes, the chain rule can be applied to any composite function as long as the derivatives of the individual functions are known. It is a fundamental rule in calculus and is used frequently in finding derivatives of more complex functions.

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