Volumes, momentos de inércia, centro de massa de objectos tridimensionais, integrais com mais de uma variável
23 Oct 2014, 14:04
Bom dia!
\(\int_{0}^{2\Pi} \int_{0}^{2} [r^2(cos\Theta +sen\Theta)+r^3]drd\Theta\)
25 Oct 2014, 05:18
Aqui vai a minha proposta de resolução:
\(\int_{0 }^{2\pi }\int_{0}^{2}\left [ r^{2}\left (cos\theta +sen\theta \right )+r^{3} \right ]drd\theta = \int_{0}^{2\pi}\left [ \frac{r^{3}}{3}(cos\theta +sen\theta )+\frac{r^{4}}{4} \right ]_{0}^{2}=\int_{0}^{2\pi }\left [\frac{8}{3}\left ( cos\theta +sen\theta \right )+4 \right ]d\theta=\left [ \frac{8}{3}\left ( sen\theta -cos\theta \right )+4\theta \right ]_{0}^{2\pi} =\frac{8}{3}\left ( sen2\pi -cos2\pi \right )+8\pi -\left [ \frac{8}{3}\left ( sen0-cos0 \right ) \right ]=-\frac{8}{3}+8\pi +\frac{8}{3}=8\pi\)
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