integral of sin(pi/6 x)

解答

\int sin (\frac{π}{6} x) d x

- \frac{6}{π} cos (\frac{π}{6} x) + C

求解步骤

\int sin (\frac{π}{6} x) d x

使用换元积分法

= \int sin (u) \frac{6}{π} d u

提出常数:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= \frac{6}{π} \cdot \int sin (u) d u

使用积分常见定则:

\int sin (u) d u = - cos (u)

= \frac{6}{π} (- cos (u))

u = \frac{π}{6} x

代回

= \frac{6}{π} (- cos (\frac{π}{6} x))

化简

= - \frac{6}{π} cos (\frac{π}{6} x)

解答补常数

= - \frac{6}{π} cos (\frac{π}{6} x) + C

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