If the radius of a circle is increased by $10 \%,$ then the corresponding area of new circle will be $\ldots \ldots \ldots . . .$
$121 \pi r^{2}$
$12.1 \pi r^{2}$
$1.21 \pi r^{2}$
None of the given three
The length of a minor arc of a circle is given by the formula $\ldots \ldots \ldots \ldots$
In the given diagram, the shaded portion represents flower bed in a plot. If $m \angle O=90, O B=21 \,m$ and $OD =14 \,m ,$ find the area of the flower bed. (in $m^2$)
In $\odot( O , r),$ minor $\widehat{ ACB }$ subtends an angle of measure $72$ at the centre. Then, the ratio of the length of minor $\widehat{A C B}$ and the circumference of the circle is ............
Find the area of a sector of circle of radius $21\, cm$ and central angle $120^{\circ}$. (in $cm ^{2}$)
If the sum of the areas of two circles with radii $R_{1}$ and $R_{2}$ is equal to the area of a circle of radius $R$, then