What will be the area of a semi-$circle$ whose perimeter is $36 \, cm$? (in $cm^2$)

$A$ sphere of $30 \ cm$ radius is dropped into a cylindrical vessel of $80 \ cm$ diameter,which is partly filled with water. If its level rises by $x \ cm$,find $x$ (in $cm$). (in $.5$)

The perimeter of a square is equal to twice the perimeter of a rectangle whose dimensions are: length $8 \, cm$ and breadth $7 \, cm$. What is the circumference of a semicircle whose diameter is equal to the side of the square? (in $cm$) (Rounded off to two decimal places)

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

If the perimeter of a right-angled isosceles triangle is $4 \sqrt{2}+4 \,m ,$ then the hypotenuse is.........$m$

The number of marble slabs of size $20 \text{ cm} \times 30 \text{ cm}$ required to pave the floor of a square room of side $3 \text{ m}$ is: