Calcolatore di integrali definiti e impropri
Calcola integrali definiti e impropri passo dopo passo
Il calcolatore cercherà di valutare l'integrale definito (cioè con estremi), inclusi quelli impropri, mostrando i passaggi.
Solution
Your input: calculate $$$\int_{\frac{\pi}{3}}^{\frac{\pi}{2}}\left( 36 \cos^{2}{\left(\theta \right)} \right)d\theta$$$
First, calculate the corresponding indefinite integral: $$$\int{36 \cos^{2}{\left(\theta \right)} d \theta}=18 \theta + 9 \sin{\left(2 \theta \right)}$$$ (for steps, see indefinite integral calculator)
According to the Fundamental Theorem of Calculus, $$$\int_a^b F(x) dx=f(b)-f(a)$$$, so just evaluate the integral at the endpoints, and that's the answer.
$$$\left(18 \theta + 9 \sin{\left(2 \theta \right)}\right)|_{\left(\theta=\frac{\pi}{2}\right)}=9 \pi$$$
$$$\left(18 \theta + 9 \sin{\left(2 \theta \right)}\right)|_{\left(\theta=\frac{\pi}{3}\right)}=\frac{9 \sqrt{3}}{2} + 6 \pi$$$
$$$\int_{\frac{\pi}{3}}^{\frac{\pi}{2}}\left( 36 \cos^{2}{\left(\theta \right)} \right)d\theta=\left(18 \theta + 9 \sin{\left(2 \theta \right)}\right)|_{\left(\theta=\frac{\pi}{2}\right)}-\left(18 \theta + 9 \sin{\left(2 \theta \right)}\right)|_{\left(\theta=\frac{\pi}{3}\right)}=- \frac{9 \sqrt{3}}{2} + 3 \pi$$$
Answer: $$$\int_{\frac{\pi}{3}}^{\frac{\pi}{2}}\left( 36 \cos^{2}{\left(\theta \right)} \right)d\theta=- \frac{9 \sqrt{3}}{2} + 3 \pi\approx 1.63054932670943$$$