• Integrals
  • Understanding the Integral of cot(x) \cot(x)

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Understanding the Integral of cot(x) \cot(x)

cot(x)dx=lnsin(x)+C\begin{align*} \boxed{\int \cot(x) \, dx = \ln|\sin(x)| + C} \end{align*}

where C C is the constant of integration.

Step-by-Step Solution:

In this article, we’ll go through the steps to find the integral of cot(x) \cot(x) . The function cot(x) \cot(x) is the ratio of cos(x) \cos(x) to sin(x) \sin(x) , which is a more convenient form when integrating.

Since cot(x)=cos(x)sin(x) \cot(x) = \dfrac{\cos(x)}{\sin(x)} :

cot(x)dx=cos(x)sin(x)dx\begin{align*} \int \cot(x) \, dx = \int \dfrac{\cos(x)}{\sin(x)} \, dx \end{align*}

To integrate this, we can use substitution. Let:

u=sin(x)\begin{align*} u = \sin(x) \end{align*}

Now, differentiate u u with respect to x x :

dudx=cos(x)dx=ducos(x)\begin{align*} \dfrac{du}{dx} = \cos(x) \Rightarrow dx = \dfrac{du}{\cos(x)} \end{align*}

Substituting u u and dx dx :

cos(x)sin(x)dx=1udu\begin{align*} \int \dfrac{\cos(x)}{\sin(x)} \, dx = \int \dfrac{1}{u} \, du \end{align*}

The integral of 1u \dfrac{1}{u} is lnu \ln|u| , so after substituting back in xx, we have:

cot(x)dx=lnsin(x)+C\begin{align*} \boxed{\int \cot(x) \, dx = \ln|\sin(x)| + C} \end{align*}

Why This Works:

By rewriting cot(x) \cot(x) as cos(x)sin(x) \dfrac{\cos(x)}{\sin(x)} , we could see that using substitution was a straightforward way to simplify the integration process. It is very common to break down trigonometric functions into cosine and sine when possible!

Final Answer:

To summarize, the integral of cot(x) \cot(x) is:

cot(x)dx=lnsin(x)+C\begin{align*} \int \cot(x) \, dx = \ln|\sin(x)| + C \end{align*}

This result is a standard problem for anyone studying integral Calculus with trigonometric functions!


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