integral from 0 to pi/(21) of tan(7x)

Lösung

\int_{0}^{\frac{π}{21}} tan (7 x) d x

\frac{1}{7} ln (2)

Dezimale

0.09902 \dots

Schritte zur Lösung

\int_{0}^{\frac{π}{21}} tan (7 x) d x

Umschreiben mit Hilfe von Trigonometrie-Identitäten

= \int_{0}^{\frac{π}{21}} \frac{sin ( 7 x )}{cos ( 7 x )} d x

Wende U-Substitution an

= \int_{1}^{\frac{1}{2}} - \frac{1}{7 u} d u

\int_{a}^{b} f (x) d x = - \int_{b}^{a} f (x) d x, a < b

= - \int_{\frac{1}{2}}^{1} - \frac{1}{7 u} d u

Entferne die Konstante:

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

= - (- \frac{1}{7} \cdot \int_{\frac{1}{2}}^{1} \frac{1}{u} d u)

Nutze das gemeinsame Integral :

\int \frac{1}{u} d u = ln (∣ u ∣)

= - (- \frac{1}{7} [ln ∣ u ∣]_{\frac{1}{2}}^{1})

Vereinfache

= \frac{1}{7} [ln ∣ u ∣]_{\frac{1}{2}}^{1}

Berechne die Grenzen:

ln (2)

= \frac{1}{7} ln (2)

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