From a circular metallic sheet with radius $21\, cm$,a regular hexagon of side $21\, cm$ is cut off. Find the area of the remaining sheet. $(\sqrt{3} = 1.73)$ (in $cm^2$)

The wheel of a motorcycle has a radius of $35 \, cm$. How many revolutions per minute must the wheel make to maintain a speed of $66 \, km/h$?

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

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

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

$\overline{ OA }$ and $\overline{ OB }$ are radii of a circle perpendicular to each other. If $OA = 5.6 \, cm$,then the area of the minor sector formed by those radii is .......... $cm^2$.