Math Problem Statement

Evaluate

Integral from nothing to nothing 10 tangent cubed x dx∫10tan3x dx.

Solution

The given integral is:

10tan3(x)dx\int 10 \tan^3(x) \, dx

Let's evaluate this step-by-step.

Step 1: Extract the constant

The integral has a constant factor of 10, which can be taken outside the integral: 10tan3(x)dx10 \int \tan^3(x) \, dx

Step 2: Express tan3(x)\tan^3(x) in terms of tan(x)\tan(x) and sec2(x)\sec^2(x)

We can rewrite tan3(x)\tan^3(x) as: tan3(x)=tan2(x)tan(x)\tan^3(x) = \tan^2(x) \cdot \tan(x) Recall that tan2(x)=sec2(x)1\tan^2(x) = \sec^2(x) - 1. Substituting this, we have: tan3(x)=(sec2(x)1)tan(x)\tan^3(x) = (\sec^2(x) - 1) \tan(x)

Thus, the integral becomes: 10(sec2(x)1)tan(x)dx10 \int (\sec^2(x) - 1) \tan(x) \, dx

Step 3: Separate the integral

We can split this into two integrals: 10(sec2(x)tan(x)dxtan(x)dx)10 \left( \int \sec^2(x) \tan(x) \, dx - \int \tan(x) \, dx \right)

Step 4: Evaluate each integral

  1. For sec2(x)tan(x)dx\int \sec^2(x) \tan(x) \, dx: Let u=tan(x)u = \tan(x), then du=sec2(x)dxdu = \sec^2(x) \, dx. Therefore, sec2(x)tan(x)dx=udu=u22=tan2(x)2\int \sec^2(x) \tan(x) \, dx = \int u \, du = \frac{u^2}{2} = \frac{\tan^2(x)}{2}

  2. For tan(x)dx\int \tan(x) \, dx: Recall the standard result: tan(x)dx=lncos(x)\int \tan(x) \, dx = -\ln |\cos(x)|

Step 5: Combine the results

Substituting back, we get: 10(tan2(x)2+lncos(x))+C10 \left( \frac{\tan^2(x)}{2} + \ln |\cos(x)| \right) + C where CC is the constant of integration.

Final Answer

5tan2(x)+10lncos(x)+C5 \tan^2(x) + 10 \ln |\cos(x)| + C

Would you like more details or have any questions about this solution?

Related Questions

  1. How do you evaluate the integral of tann(x)\tan^n(x) for any positive integer nn?
  2. What are the integrals of other trigonometric functions like sec3(x)\sec^3(x) or csc3(x)\csc^3(x)?
  3. How can you verify an integral result using differentiation?
  4. What substitution methods are commonly useful in integrating trigonometric expressions?
  5. How would you handle the integral if it had different limits?

Tip: Remember that trigonometric identities, such as tan2(x)=sec2(x)1\tan^2(x) = \sec^2(x) - 1, are often helpful for simplifying integrals involving powers of trigonometric functions.

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Math Problem Analysis

Mathematical Concepts

Integral Calculus
Trigonometric Integrals

Formulas

∫tan^3(x) dx
tan^2(x) = sec^2(x) - 1
∫tan(x) dx = -ln|cos(x)|

Theorems

Trigonometric Identity for tan^2(x)
Substitution in Integration

Suitable Grade Level

College Level (Calculus 1/2)