Evaluated: int_(-3/4)^(3/4)( dx) / (√(9-4x^2)
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সঠিক উত্তরঃ
A.
π/6
Explanation:

Another Explanation (5):
সমাধান:
\[
\int_{-\frac{3}{4}}^{\frac{3}{4}} \frac{dx}{\sqrt{9-4x^2}}
\]
ধরি, \( x = \frac{3}{2} \sin(\theta) \). তাহলে, \( dx = \frac{3}{2} \cos(\theta) d\theta \). 😃
যখন \( x = -\frac{3}{4} \),
\[
-\frac{3}{4} = \frac{3}{2} \sin(\theta) \implies \sin(\theta) = -\frac{1}{2} \implies \theta = -\frac{\pi}{6}
\]
যখন \( x = \frac{3}{4} \),
\[
\frac{3}{4} = \frac{3}{2} \sin(\theta) \implies \sin(\theta) = \frac{1}{2} \implies \theta = \frac{\pi}{6}
\]
সুতরাং, ইন্টিগ্রালটি হবে:
\[
\int_{-\frac{\pi}{6}}^{\frac{\pi}{6}} \frac{\frac{3}{2} \cos(\theta) d\theta}{\sqrt{9 - 4(\frac{9}{4} \sin^2(\theta))}} = \int_{-\frac{\pi}{6}}^{\frac{\pi}{6}} \frac{\frac{3}{2} \cos(\theta) d\theta}{\sqrt{9 - 9\sin^2(\theta)}}
\]
\[
= \int_{-\frac{\pi}{6}}^{\frac{\pi}{6}} \frac{\frac{3}{2} \cos(\theta) d\theta}{3\sqrt{1 - \sin^2(\theta)}} = \int_{-\frac{\pi}{6}}^{\frac{\pi}{6}} \frac{\frac{3}{2} \cos(\theta) d\theta}{3\cos(\theta)}
\]
\[
= \int_{-\frac{\pi}{6}}^{\frac{\pi}{6}} \frac{1}{2} d\theta = \frac{1}{2} [\theta]_{-\frac{\pi}{6}}^{\frac{\pi}{6}} = \frac{1}{2} \left( \frac{\pi}{6} - \left(-\frac{\pi}{6}\right) \right)
\]
\[
= \frac{1}{2} \left( \frac{\pi}{6} + \frac{\pi}{6} \right) = \frac{1}{2} \left( \frac{2\pi}{6} \right) = \frac{\pi}{6}
\]
অতএব,
\[
\int_{-\frac{3}{4}}^{\frac{3}{4}} \frac{dx}{\sqrt{9-4x^2}} = \frac{\pi}{6}
\]
🎉🎉