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Difficulty: Medium Type: Single Choice

If θ is the angle of intersection of two curves, then,

(tan \ θ = \left | \frac{m_{1}-m_{2}}{1 + m_{1}m_{2}} \right |)

Comprehension

Let $\mathrm{z} \in \mathrm{C}$ and $\mathrm{z}_{\mathrm{r}}(\mathrm{r}=\mathbf{1}, 2,3,4)$ satisfy the equation $|z+\bar{z}-4|+3|z-\bar{z}-2 i|=12$ such that $\left|z_r-(2+i)\right|$ is least.

$\sum_{r=1}^4\left|\operatorname{Re}\left(z_r\right)\right|$ is equal to

  1. 8
  2. $12 / 5$
  3. $8 / 5$
  4. $4 / 5$

  5. The value of definite integral $\int_{\frac{-1}{\sqrt{3}}}^{\frac{1}{\sqrt{3}}} \frac{\cos ^{-1}\left(\frac{2 x}{1+x^{2}}\right)+\tan ^{-1}\left(\frac{2 x}{1-x^{2}}\right)}{e^{x}+1} d x$ is equal to:
Diagram

(b) $\frac{\pi}{\sqrt{3}}$

(c) $\frac{\pi}{4 \sqrt{3}}$

(d) $\frac{\pi}{3 \sqrt{3}}$

  • $12 / 5$
  • $4 / 5$ ✔️
  • $8 / 5$
  • (a) $\frac{\pi}{2 \sqrt{3}}$

Solution

The value of definite integral $\int_{\frac{-1}{\sqrt{3}}}^{\frac{1}{\sqrt{3}}} \frac{\cos ^{-1}\left(\frac{2 x}{1+x^{2}}\right)+\tan ^{-1}\left(\frac{2 x}{1-x^{2}}\right)}{e^{x}+1} d x$ is equal to:

(b) $\frac{\pi}{\sqrt{3}}$

(c) $\frac{\pi}{4 \sqrt{3}}$

Diagram

(d) $\frac{\pi}{3 \sqrt{3}}$