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Derivatan av $$$\ln\left(\sin{\left(x \right)}\right)$$$
Relaterade kalkylatorer: Kalkylator för logaritmisk derivering, Räknare för implicit derivering med steg
Din inmatning
Bestäm $$$\frac{d}{dx} \left(\ln\left(\sin{\left(x \right)}\right)\right)$$$.
Lösning
Funktionen $$$\ln\left(\sin{\left(x \right)}\right)$$$ är sammansättningen $$$f{\left(g{\left(x \right)} \right)}$$$ av två funktioner $$$f{\left(u \right)} = \ln\left(u\right)$$$ och $$$g{\left(x \right)} = \sin{\left(x \right)}$$$.
Tillämpa kedjeregeln $$$\frac{d}{dx} \left(f{\left(g{\left(x \right)} \right)}\right) = \frac{d}{du} \left(f{\left(u \right)}\right) \frac{d}{dx} \left(g{\left(x \right)}\right)$$$:
$${\color{red}\left(\frac{d}{dx} \left(\ln\left(\sin{\left(x \right)}\right)\right)\right)} = {\color{red}\left(\frac{d}{du} \left(\ln\left(u\right)\right) \frac{d}{dx} \left(\sin{\left(x \right)}\right)\right)}$$Derivatan av den naturliga logaritmen är $$$\frac{d}{du} \left(\ln\left(u\right)\right) = \frac{1}{u}$$$:
$${\color{red}\left(\frac{d}{du} \left(\ln\left(u\right)\right)\right)} \frac{d}{dx} \left(\sin{\left(x \right)}\right) = {\color{red}\left(\frac{1}{u}\right)} \frac{d}{dx} \left(\sin{\left(x \right)}\right)$$Återgå till den ursprungliga variabeln:
$$\frac{\frac{d}{dx} \left(\sin{\left(x \right)}\right)}{{\color{red}\left(u\right)}} = \frac{\frac{d}{dx} \left(\sin{\left(x \right)}\right)}{{\color{red}\left(\sin{\left(x \right)}\right)}}$$Derivatan av sinus är $$$\frac{d}{dx} \left(\sin{\left(x \right)}\right) = \cos{\left(x \right)}$$$:
$$\frac{{\color{red}\left(\frac{d}{dx} \left(\sin{\left(x \right)}\right)\right)}}{\sin{\left(x \right)}} = \frac{{\color{red}\left(\cos{\left(x \right)}\right)}}{\sin{\left(x \right)}}$$Förenkla:
$$\frac{\cos{\left(x \right)}}{\sin{\left(x \right)}} = \frac{1}{\tan{\left(x \right)}}$$Alltså, $$$\frac{d}{dx} \left(\ln\left(\sin{\left(x \right)}\right)\right) = \frac{1}{\tan{\left(x \right)}}$$$.
Svar
$$$\frac{d}{dx} \left(\ln\left(\sin{\left(x \right)}\right)\right) = \frac{1}{\tan{\left(x \right)}}$$$A