Math Problem Statement

∫ 0 π/4 ​ sin(2x)dx

Solution

To evaluate the integral 0π4sin(2x)dx\int_{0}^{\frac{\pi}{4}} \sin(2x) \, dx, we can follow these steps:

  1. Substitute: Let u=2xu = 2x. Then, du=2dxdu = 2 \, dx, or equivalently, dx=du2dx = \frac{du}{2}.

  2. Change the limits of integration: When x=0x = 0, u=20=0u = 2 \cdot 0 = 0. When x=π4x = \frac{\pi}{4}, u=2π4=π2u = 2 \cdot \frac{\pi}{4} = \frac{\pi}{2}.

  3. Rewrite the integral: The integral becomes: 0π4sin(2x)dx=0π2sin(u)12du=120π2sin(u)du\int_{0}^{\frac{\pi}{4}} \sin(2x) \, dx = \int_{0}^{\frac{\pi}{2}} \sin(u) \cdot \frac{1}{2} \, du = \frac{1}{2} \int_{0}^{\frac{\pi}{2}} \sin(u) \, du

  4. Evaluate the integral: We know the antiderivative of sin(u)\sin(u) is cos(u)-\cos(u). So: 120π2sin(u)du=12[cos(u)]0π2\frac{1}{2} \int_{0}^{\frac{\pi}{2}} \sin(u) \, du = \frac{1}{2} \left[ -\cos(u) \right]_{0}^{\frac{\pi}{2}}

  5. Apply the limits: [ \frac{1}{2} \left[ -\cos\left(\frac{\pi}{2}\right) + \cos(0) \right] = \frac{1}{2} \left[ -0 + 1 \right] = \frac{1}{2} \cdot 1 = \frac{1}{2} ]

Therefore, the value of the integral 0π4sin(2x)dx\int_{0}^{\frac{\pi}{4}} \sin(2x) \, dx is 12\frac{1}{2}.

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

Here are some related questions for further practice:

  1. Evaluate 0π2cos(3x)dx\int_{0}^{\frac{\pi}{2}} \cos(3x) \, dx.
  2. Evaluate 0πsin(4x)dx\int_{0}^{\pi} \sin(4x) \, dx.
  3. Find the antiderivative of sin(kx)\sin(kx) for a constant kk.
  4. Evaluate 0π3sin(2x)dx\int_{0}^{\frac{\pi}{3}} \sin(2x) \, dx.
  5. Find 0π6sin(5x)dx\int_{0}^{\frac{\pi}{6}} \sin(5x) \, dx.
  6. Compute 01sin(2πx)dx\int_{0}^{1} \sin(2\pi x) \, dx.
  7. Determine π4π2sin(2x)dx\int_{\frac{\pi}{4}}^{\frac{\pi}{2}} \sin(2x) \, dx.
  8. Evaluate 0π4cos(2x)dx\int_{0}^{\frac{\pi}{4}} \cos(2x) \, dx.

Tip: When dealing with integrals involving trigonometric functions, substitution can often simplify the process.

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Math Problem Analysis

Mathematical Concepts

Integral calculus
Trigonometric substitution

Formulas

Substitution method for integrals

Theorems

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Suitable Grade Level

Advanced High School