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 $.8$)?

If the length of one diagonal of a rhombus is $80 \%$ of the length of the other diagonal,the area of the rhombus is how many times the square of the length of the longer diagonal?

If the area of a square increases by $69 \%$,then the side of the square increases by (in $\%$)

The hypotenuse and the semi-perimeter of a right triangle are $20\, cm$ and $24\, cm$,respectively. The other two sides of the triangle are

$A$ circle and a rectangle have the same perimeter. The sides of the rectangle are $18 \, cm$ and $26 \, cm$. What is the area of the circle? (in $cm^2$)

$A$ drawing room is $7.5 \text{ m}$ long,$6.5 \text{ m}$ broad,and $6 \text{ m}$ high. Find the length of paper $2.5 \text{ dm}$ wide required to cover its walls,allowing $8 \text{ m}^2$ for doors.