In a circle of radius $42\, cm,$ an arc subtends an angle of $72^{\circ}$ at the centre. The length of the arc is.....$cm$ (in $.8$)?

$A$ circular wire of diameter $112 \, cm$ is cut and bent in the form of a rectangle whose sides are in the ratio of $9:7$. The small side of the rectangle is......$cm$.

$A$ circle is inscribed in an equilateral triangle of side $8 \text{ cm}$. The area of the portion between the triangle and the circle is ...... $\text{cm}^2$.

Find the diameter of a wheel that makes $113$ revolutions to go $2 \, km$ $26 \, decametres$. (in $m$)

$A$ solid metallic sphere of radius $21\, cm$ is melted and recast into a cone with diameter of the base as $21\, cm$. What is the height (in $cm$) of the cone?

In a right-angled triangle,find the hypotenuse if the base and perpendicular are respectively $36015 \ cm$ and $48020 \ cm$.