If the radius of a circle is increased by $10 \%,$ its area will increase by $\ldots \ldots \ldots . \%$

If the circumference of a circle and the perimeter of a square are equal,then

The length of a diagonal of a square is $8 \sqrt{2}$. Then,its area is $\ldots \ldots \ldots$

The diameters of front and rear wheels of a tractor are $80 \,cm$ and $2 \,m$ respectively. Find the number of revolutions that the rear wheel will make in covering a distance in which the front wheel makes $1400$ revolutions.

The maximum area of $\Delta ABC$ inscribed in a semicircle with radius $10 \, cm$ is ....... $cm^2$.

Find the diameter of the circle whose area is equal to the sum of the areas of the two circles of diameters $20 \, cm$ and $48 \, cm$. (in $cm$)