In a circle with radius $6 \, cm$,the area of a sector corresponding to an arc of length $12 \, cm$ is $\ldots \ldots \ldots \, cm^2$.

Is it true to say that the area of a segment of a circle is less than the area of its corresponding sector? Why?

On a square cardboard sheet of area $784 \, cm^{2}$, four congruent circular plates of maximum size are placed such that each circular plate touches the other two plates and each side of the square sheet is tangent to two circular plates. Find the area of the square sheet not covered by the circular plates (in $cm^{2}$).

In $\odot(O, r)$,the length of minor $\widehat{ACB}$ is $\frac{1}{6}$ times the circumference of the circle. Then,the measure of the angle subtended at the centre by minor $\widehat{ACB}$ is ......... (in $^{\circ}$)

In a circle with radius $42 \, cm$,an arc subtends an angle of $120^{\circ}$ at the centre. Find the length of this arc and the area of the sector formed by this arc.

As shown in the diagram, rectangle $ABCD$ is a metal sheet in which $CD = 20 \, cm$ and $BC = 14 \, cm$. From it, a semicircle with diameter $\overline{BC}$ and a sector with centre $A$ and radius $AD$ is cut off. Find the area of the remaining sheet in $cm^2$.