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Integral of sin⁡(8x)\sin\left(8 x\right)

The integral of sin⁡(8x)\sin\left(8 x\right) is −cos⁡(8x)8+C\frac{-\cos\left(8 x\right)}{8} + C.

Graph of f(x) = sin(8x) with the area from 0 to π shaded-112345-1-0.50.51f(x)
Graph of f(x) = sin(8x) with the area from 0 to π shaded. The shaded area equals the definite integral, about 0.

How to work it out

  1. 1

    We want an antiderivative of f(x) = sin(8x).

    ∫sin⁡(8x) dx\int \sin\left(8 x\right)\,dx
  2. 2

    Method: ∫sin(kx) dx = −cos(kx)/k.

  3. 3

    That gives the antiderivative; add the constant C because any constant disappears when you differentiate:

    ∫sin⁡(8x) dx=−cos⁡(8x)8+C\int \sin\left(8 x\right)\,dx = \frac{-\cos\left(8 x\right)}{8} + C
  4. 4

    Check by differentiating the answer; you must get the original function back:

    ddx[−cos⁡(8x)8]=64sin⁡(8x)64\frac{d}{dx}\left[\frac{-\cos\left(8 x\right)}{8}\right] = \frac{64 \sin\left(8 x\right)}{64}
  5. 5

    As a definite integral, evaluate the antiderivative at both ends and subtract. Between 0 and π:

    ∫0πsin⁡(8x) dx=[−cos⁡(8x)8]0π≈0\int_{0}^{\pi} \sin\left(8 x\right)\,dx = \Big[\frac{-\cos\left(8 x\right)}{8}\Big]_{0}^{\pi} \approx 0
LaTeX source of the formulas on this page
\[ \int \sin\left(8 x\right)\,dx = \frac{-\cos\left(8 x\right)}{8} + C \]
\[ \int \sin\left(8 x\right)\,dx \]
\[ \frac{d}{dx}\left[\frac{-\cos\left(8 x\right)}{8}\right] = \frac{64 \sin\left(8 x\right)}{64} \]
\[ \int_{0}^{\pi} \sin\left(8 x\right)\,dx = \Big[\frac{-\cos\left(8 x\right)}{8}\Big]_{0}^{\pi} \approx 0 \]

Definite integrals of the same function

IntervalValue
from 0 to π0
from 0 to π/20

Questions

What is the integral of sin(8x)?

The integral of sin⁡(8x)\sin\left(8 x\right) is −cos⁡(8x)8+C\frac{-\cos\left(8 x\right)}{8} + C.

Why do we add + C?

Every function F(x) + C has the same derivative, so the antiderivative is only defined up to a constant.

What is the integral of sin(8x) from 0 to π?

About 0.

More integrals

    Integral of sin(8x): -cos(8x) / 8 + C (with steps) | WordGPT