What is the antiderivative of cosecant?

Understand the Problem

The question is asking for the antiderivative (or integral) of the cosecant function (csc). The approach to solve this involves using integration techniques and identities related to trigonometric functions.

Answer

$-\ln|\text{csc}(x) + \text{cot}(x)| + C$
Answer for screen readers

The final answer is $-\ln|\text{csc}(x) + \text{cot}(x)| + C$

Steps to Solve

  1. Rewrite $ ext{csc}(x)$ in terms of known integrals

    To make the integral easier to solve, rewrite $ ext{csc}(x)$ as $ rac{1}{ ext{sin}(x)}$.

    $$ ext{csc}(x) = rac{1}{ ext{sin}(x)}$$

  2. Multiply and divide by $ ext{csc}(x) + ext{cot}(x)$

    Multiply and divide the integrand by $ ext{csc}(x) + ext{cot}(x)$ to create a more solvable form.

    $$\int ext{csc}(x) , dx = \int \text{csc}(x) \cdot \frac{\text{csc}(x) + \text{cot}(x)}{\text{csc}(x) + \text{cot}(x)} , dx$$

  3. Simplify the integral

    Simplify the integral to isolate a more straightforward derivative form

    $$\int \frac{\text{csc}^2(x) + \text{csc}(x) \text{cot}(x)}{\text{csc}(x) + \text{cot}(x)} , dx$$

  4. Use substitution to solve the integral

    Let $u = \text{csc}(x) + \text{cot}(x)$, then calculate $du$.

    $$du = -(\text{csc}(x) \text{cot}(x) + \text{csc}^2(x)) , dx$$

    Hence,

    $$\int \frac{-1}{u} , du$$

  5. Integrate and solve

    Integrate the function with respect to $u$.

    $$-\ln|u| + C$$ where $C$ is the constant of integration.

  6. Substitute $u$ back in

    Replace $u$ with $\text{csc}(x) + \text{cot}(x)$.

    $$-\ln|\text{csc}(x) + \text{cot}(x)| + C$$

The final answer is $-\ln|\text{csc}(x) + \text{cot}(x)| + C$

More Information

This integral is interesting because it is not immediately obvious and requires a clever substitution and manipulation to solve.

Tips

A common mistake is forgetting to use the absolute value inside the logarithm function or not correctly simplifying the expression for $du$ in terms of $dx$.

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