While calculating the area of a circle, its radius was taken to be $6\,cm$ instead of $5\,cm .$ The calculated area is $\ldots \ldots \ldots . . \%$ more than the actual area.
$20$
$24$
$44$
$40$
Find the radius of a circle whose circumference is equal to the sum of the circumferences of two circles of radii $15 \,cm$ and $18 \,cm$ (in $cm$)
In $Fig.$ arcs have been drawn of radius $21\, cm$ each with vertices $A , B , C$ and $D$ of quadrilateral $A B C D$ as centres. Find the area of the shaded region. (in $cm ^{2}$)
The maximum area of a triangle inscribed in a semicircle with diameter $50 \,cm$ is........... $cm^{2}$
The area of a circle is $3850\, cm ^{2} .$ In that circle, the length of an arc subtending a right angle at the centre is $\ldots \ldots \ldots . cm$.
The ratio of radii of two circles is $4: 5.$ Then, the ratio of their areas is...........