The circumference of a circle with radius $8.4\,cm$ is $\ldots \ldots \ldots \ldots cm$.

A calf is tied with a rope of length $6 \,m$ at the corner of a square grassy lawn of side $20\, m$. If the length of the rope is increased by $5.5\, m$, find the increase in area of the grassy lawn in which the calf can graze. (in $m ^{2}$)

The length of diagonals of 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 segment the centre of which is the point of intersection of diagonals. Find the area of these flower beds. $(\pi=3.14)$ (in $m^2$)

As shown in the diagram, the length of square garden $ABCD$ is $60\, m$. Flower beds are prepared in the shape of segment on two opposite sides of the square. The centre of the segments is the point of intersection of the diagonals of square $ABCD.$ Find the area of the flower beds. $(\pi=3.14)$ (in $m^2$)

Find the difference of the areas of a sector of angle $120^{\circ}$ and its corresponding major sector of a circle of radius $21\, cm .$ (in $cm^2$)

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