$A$ wire fence is to be put up all around a circular ground with diameter $105 \, m$. The length of the fence is $\ldots \ldots \ldots \ldots \, m$.

With respect to the given diagram,which of the following correctly matches the information in Part $I$ and Part $II$?

Part $I$	Part $II$
$1. \overline{OA} \cup \overline{OB} \cup \widehat{APB}$	$a. \text{Major sector}$
$2. \overline{AB} \cup \widehat{AQB}$	$b. \text{Minor segment}$
$3. \overline{AB} \cup \widehat{APB}$	$c. \text{Minor sector}$
$4. \overline{OA} \cup \overline{OB} \cup \widehat{AQB}$	$d. \text{Major segment}$

In a circle with radius $8.4 \, cm$,two radii are perpendicular to each other. The area of the minor sector formed by these radii is $\ldots \ldots \ldots \, cm^2$.

In $\odot(O, 12)$, minor $\widehat{ACB}$ subtends an angle of measure $30^{\circ}$ at the centre. Then, the length of major $\widehat{ADB}$ is $\ldots \ldots \ldots \text{ cm}$. (in $\pi$)

In a circle with radius $6.3 \ cm$,an arc subtends an angle of measure $150^{\circ}$ at the centre. Find the length of this arc and the area of the sector formed by this arc.

In $\odot(O, 5.6)$,$\overline{OA}$ and $\overline{OB}$ are radii perpendicular to each other. Then,the difference between the area of the minor sector formed by minor $\widehat{AB}$ and the corresponding minor segment is $\ldots \ldots \ldots \ldots cm^2$.