int_0^fracπ2cos^3x sqrtsinxdx
RUUnit-Hউচ্চতর গণিত প্রথম পত্রযোগজীকরণsin ও cosine সংক্রান্ত যোগজ (Topic Practice)RU - ⚡ অনলাইন প্রশ্নব্যাংক দেখুন 💥
সঠিক উত্তরঃ
D.
8/21
Explanation:
Type explanation here...
Another Explanation (5):
সমাধান:
ধরি, \( sinx = t^2 \)
∴ \( cosx dx = 2t dt \)
\( \int_{0}^{\frac{\pi}{2}} cos^3x \sqrt{sinx} dx \)
\( = \int_{0}^{\frac{\pi}{2}} cos^2x \sqrt{sinx} cosx dx \)
\( = \int_{0}^{\frac{\pi}{2}} (1-sin^2x) \sqrt{sinx} cosx dx \)
এখন, \( sinx = t^2 \) হলে, \( cosx dx = 2t dt \)
যখন \( x = 0 \), \( t = 0 \) এবং যখন \( x = \frac{\pi}{2} \), \( t = 1 \)
সুতরাং, \( \int_{0}^{\frac{\pi}{2}} (1-sin^2x) \sqrt{sinx} cosx dx \)
\( = \int_{0}^{1} (1-t^4) \sqrt{t^2} 2t dt \)
\( = 2 \int_{0}^{1} (1-t^4) t^2 dt \)
\( = 2 \int_{0}^{1} (t^2 - t^6) dt \)
\( = 2 \left[ \frac{t^3}{3} - \frac{t^7}{7} \right]_{0}^{1} \)
\( = 2 \left[ \frac{1}{3} - \frac{1}{7} \right] \)
\( = 2 \left[ \frac{7-3}{21} \right] \)
\( = 2 \left[ \frac{4}{21} \right] \)
\( = \frac{8}{21} \) 🎉