Math Problem Statement

Evaluate the integral of cot^2(x) dx.

Solution

The expression in the image is:

cot2(x)dx\int \cot^2(x) \, dx

To solve this integral, we can proceed by using trigonometric identities. Here's the detailed process:

Step 1: Rewrite cot2(x)\cot^2(x) using a trigonometric identity

We know that: cot2(x)=csc2(x)1\cot^2(x) = \csc^2(x) - 1 This identity comes from the Pythagorean identity for cotangent: csc2(x)=1+cot2(x)\csc^2(x) = 1 + \cot^2(x) So the integral becomes: cot2(x)dx=(csc2(x)1)dx\int \cot^2(x) \, dx = \int (\csc^2(x) - 1) \, dx

Step 2: Break the integral into two simpler integrals

(csc2(x)1)dx=csc2(x)dx1dx\int (\csc^2(x) - 1) \, dx = \int \csc^2(x) \, dx - \int 1 \, dx

Step 3: Integrate both terms

  1. The integral of csc2(x)\csc^2(x) is cot(x)-\cot(x): csc2(x)dx=cot(x)\int \csc^2(x) \, dx = -\cot(x)
  2. The integral of 11 is just xx: 1dx=x\int 1 \, dx = x

Step 4: Combine the results

So, the integral becomes: cot(x)x+C-\cot(x) - x + C where CC is the constant of integration.

Final Answer:

cot2(x)dx=cot(x)x+C\int \cot^2(x) \, dx = -\cot(x) - x + C

Let me know if you'd like any further details or clarification!

Related Questions:

  1. What are the other Pythagorean identities used in trigonometry?
  2. How do you integrate csc(x)\csc(x) and sec(x)\sec(x) functions?
  3. Can the integral of cot2(x)\cot^2(x) be solved using substitution methods?
  4. What is the integral of sec2(x)\sec^2(x)?
  5. How do we derive the identity cot2(x)=csc2(x)1\cot^2(x) = \csc^2(x) - 1?

Tip:

Memorizing basic trigonometric integrals like csc2(x)dx\int \csc^2(x) dx and sec2(x)dx\int \sec^2(x) dx can significantly speed up solving trigonometric integrals!

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Math Problem Analysis

Mathematical Concepts

Calculus
Trigonometry
Integration

Formulas

cot^2(x) = csc^2(x) - 1
∫ cot^2(x) dx = ∫ (csc^2(x) - 1) dx
∫ csc^2(x) dx = -cot(x)
∫ 1 dx = x

Theorems

Pythagorean Identity for Cotangent

Suitable Grade Level

College Level