MCQ
The integral $\int_{0}^{\frac{\pi}{2}} \frac{1}{3+2 \sin x+\cos x} d x$ is equal to.
- A$\tan ^{-1}(2)$
- ✓$\tan ^{-1}(2)-\frac{\pi}{4}$
- C$\frac{1}{2} \tan ^{-1}(2)-\frac{\pi}{8}$
- D$\frac{1}{2}$
Put $\tan \frac{x}{2}=t$, so
$I=\int_{0}^{1} \frac{d t}{(t+1)^{2}+1}=\left.\tan ^{-1}(x+1)\right|_{0} ^{1}=\tan ^{-1} 2-\frac{\pi}{4}$
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$I$. If $9$ divides $a^3+b^3+c^3$, then $3$ divides $a b c$.
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