28. The integral $\int _ { 1 / 2 - 1 / 2 } ( [ x ] + \ln ( 1 + x / 1 + x ) ) d x$ equals\\
(A) $- 1 / 2$\\
(B) 0\\
(C) 1\\
(D) $2 \ln ( 1 / 2 )$

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\begin{enumerate}
  \setcounter{enumi}{28}
  \item If vector $a$ and bare two vectors such that $a \rightarrow + 2 b \rightarrow$ and $5 a \rightarrow - 4 b \rightarrow$ are perpendicular to each other then the angle between vector $a$ and $b$ is\\
(A) $\quad 45 ^ { \circ }$\\
(B) $\quad 60 ^ { 0 }$\\
(C) $\quad \cos ^ { - 1 } 1 / 3$\\
(D) $\quad \cos ^ { - 1 } 2 / 7$
  \item Let vector $\mathrm { V } = 2 \mathrm { i } ^ { \rightarrow } + \mathrm { j } ^ { \rightarrow } - \mathrm { k } ^ { \rightarrow }$ and $\mathrm { W } ^ { \rightarrow } = \mathrm { i } ^ { \rightarrow } + 3 \mathrm { k } ^ { \rightarrow }$. If vector U is a unit vector, then the maximum value of the scalar triple product $\left[ \mathrm { U } ^ { \rightarrow } \mathrm { V } ^ { \rightarrow } \mathrm { W } ^ { \rightarrow } \right]$ is\\
(A) - 1\\
(B) $\quad \sqrt { } 10 + \sqrt { } 6$\\
(C) $\sqrt { } 59$\\
(D) $\sqrt { } 60$
\end{enumerate}