- A$\frac{5}{2}$
- ✓$\frac{3}{2}$
- C$\frac{1}{2}$
- D$\frac{2}{5}$
$= \int_{\pi /3}^{\pi /2} {\,\,\frac{{\sin x}}{{{{(1 - \cos x)}^3}}}\,dx} $
Now, put $1 - \cos x = t$
Also, when $x = \frac{\pi }{3},t = \frac{1}{2}$ and $x = \frac{\pi }{2}\,,\,\,t = 1$
Therefore, $I = \int_{1/2}^1 {\frac{{dt}}{{{t^3}}} = \left| {\frac{{{t^{ - 2}}}}{{ - 2}}} \right|} _{1/2}^1 = \frac{3}{2}$.
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($1$) Let $p_i$ be the probability that a randomly chosen point has $i$ many friends, $i=0,1,2,3,4$. Let $X$ be a random variable such that for $i=0,1,2,3,4$, the probability $P(X=i)=p_i$. Then the value of $7 E(X)$ is
($2$) Two distinct points are chosen randomly out of the points $A_1, A_2, \ldots, A_{4 g}$. Let $p$ be the probability that they are friends. Then the value of $7 p$ is