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

The radius of a circle is $3.5\,cm$. The area of the minor sector formed by two perpendicular radii of that circle is $\ldots \ldots \ldots \,cm^2$.

If the perimeter of a circle is equal to that of a square,then the ratio of their areas is

The ratio of the areas of $\odot(O, 6)$ and $\odot(P, 12)$ is ...........

In the figure,arcs have been drawn with radii $14 \, cm$ each and with centres $P$,$Q$,and $R$. Find the area of the shaded region (in $cm^{2}$).

An archery target has three regions formed by three concentric circles as shown in the figure. If the diameters of the concentric circles are in the ratio $1: 2: 3$,then find the ratio of the areas of the three regions.