The area of a circle is $38.5\, m^2$,then its circumference will be $\ldots \ldots \ldots \ldots \, m$.

In $\odot(O, 4 \, cm)$,the length of chord $\overline{AB}$ is $4 \, cm$. Then,$m \angle AOB = \ldots$ (in $^\circ$)

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

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.

The diameter of a circular garden is $210 \,m$. Inside it,all along the boundary,there is a path of uniform width $7 \,m$. Then,the area of the path is $\ldots \ldots \ldots \ldots \,m^2$.

The length of the diagonals of a square garden $ABCD$ is $120\, m$. As shown in the figure,there are flower beds on two opposite sides of the garden in the shape of minor segments,the center of which is the point of intersection of the diagonals. Find the area of these flower beds. $(\pi=3.14)$ (in $m^2$)