Math Problem Statement

indefinite integral of sin^3xcos^2xdx

Solution

To find the indefinite integral of sin3(x)cos2(x)dx\sin^3(x) \cos^2(x) \, dx, we can use trigonometric identities and substitution methods. Here’s a step-by-step solution:

Step 1: Rewrite the integrand using trigonometric identities

We know the identity: sin2(x)=1cos2(x)\sin^2(x) = 1 - \cos^2(x) So we can rewrite sin3(x)\sin^3(x) as: sin3(x)=sin(x)sin2(x)=sin(x)(1cos2(x))\sin^3(x) = \sin(x) \cdot \sin^2(x) = \sin(x) \cdot (1 - \cos^2(x)) Thus, the integral becomes: sin3(x)cos2(x)dx=sin(x)(1cos2(x))cos2(x)dx\int \sin^3(x) \cos^2(x) \, dx = \int \sin(x) (1 - \cos^2(x)) \cos^2(x) \, dx Expanding the integrand: sin(x)cos2(x)dxsin(x)cos4(x)dx\int \sin(x) \cos^2(x) \, dx - \int \sin(x) \cos^4(x) \, dx

Step 2: Use substitution

Let u=cos(x)u = \cos(x), then du=sin(x)dxdu = -\sin(x) \, dx. The integrals become: u2du+u4du-\int u^2 \, du + \int u^4 \, du The negative sign comes from the substitution du=sin(x)dxdu = -\sin(x) \, dx.

Step 3: Integrate

Now integrate each term: u2du=u33=cos3(x)3-\int u^2 \, du = -\frac{u^3}{3} = -\frac{\cos^3(x)}{3} u4du=u55=cos5(x)5\int u^4 \, du = \frac{u^5}{5} = \frac{\cos^5(x)}{5}

Step 4: Combine the results

Combine the results to get the final answer: sin3(x)cos2(x)dx=cos3(x)3+cos5(x)5+C\int \sin^3(x) \cos^2(x) \, dx = -\frac{\cos^3(x)}{3} + \frac{\cos^5(x)}{5} + C where CC is the constant of integration.

Final Answer

sin3(x)cos2(x)dx=cos3(x)3+cos5(x)5+C\boxed{\int \sin^3(x) \cos^2(x) \, dx = -\frac{\cos^3(x)}{3} + \frac{\cos^5(x)}{5} + C}

Would you like a detailed explanation of any particular step or have any questions?

Here are some related questions you might find interesting:

  1. What is the indefinite integral of sin2(x)cos3(x)dx\sin^2(x) \cos^3(x) \, dx?
  2. How would you integrate sin4(x)cos2(x)dx\sin^4(x) \cos^2(x) \, dx?
  3. Can you find the indefinite integral of sin2(x)cos4(x)dx\sin^2(x) \cos^4(x) \, dx?
  4. What substitution would you use for sin3(x)cos(x)dx\sin^3(x) \cos(x) \, dx?
  5. How would you solve sin(x)cos(x)dx\int \sin(x) \cos(x) \, dx using a double-angle identity?

Tip: When integrating trigonometric functions raised to powers, always consider using identities or substitutions to simplify the expression.

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Math Problem Analysis

Mathematical Concepts

Integration
Trigonometric Identities
Substitution Method

Formulas

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Theorems

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Suitable Grade Level

Advanced High School