Let $\mathrm{f}(\mathrm{x}) \begin{cases}=\mathrm{x}+\mathrm{a} \sqrt{2} \sin \mathrm{x}, & 0 \leq…
- $a=\frac{\pi}{6}, b=\frac{-\pi}{12}$
- $\mathrm{a}=\frac{-\pi}{6}, \mathrm{~b}=\frac{-\pi}{12}$
- $a=\frac{-\pi}{6}, b=\frac{\pi}{12}$
- $\mathrm{a}=\frac{\pi}{6}, \mathrm{~b}=\frac{\pi}{12}$
Solution
$\lim _{x \rightarrow \frac{\pi^{+}}{4}} f(x)=\lim _{x \rightarrow \frac{\pi^{+}}{4}} 2 x \cot x+b$
$\lim _{x \rightarrow \frac{\pi^{-}}{2}} f(x)=\lim _{x \rightarrow \frac{\pi^{-}}{2}} 2 x \cot x+b$
$\begin{aligned} & \lim _{x \rightarrow \frac{\pi^{+}}{2}} f(x)=\lim _{x \rightarrow \frac{\pi^{+}}{2}} a \cos 2 x-b \sin x \\ & =a \cos 2\left(\frac{\pi}{2}\right)-b \sin \left(\frac{\pi}{2}\right)\end{aligned}$
Since $f(x)$ is continuous at $\frac{\pi}{4}$ and $\frac{\pi}{2}$, we write
$\frac{\pi}{4}+\mathrm{a}=\frac{\pi}{2}+\mathrm{b} \quad \ldots[$ From (1) and (2) $]$
$\mathrm{b}=-\mathrm{a}-\mathrm{b} \quad \ldots[$ From (3) and (4) $]$
Asked in: MHT CET 2021 (22 Sep Shift 2)
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