Find the ratio of areas of inscribed square in a semicircle and a circle while the radii of circle and semicircle are equal.

Semi-circular lawns are attached to all the edges of a rectangular field measuring $42 \mathrm{m}\times 35 \mathrm{m}$. The area of the total field is_____

A bicycle wheel makes $5000$ revolutions in moving $11 \mathrm{km}.$ Then the radius of the wheel (in cm) is (Take $\pi = \frac{22}{7}$)

If a wire is bent into the shape of a square, then the area of the square so formed is $81 {\mathrm{cm}}^2$. When the wire is rebent into a semicircular shape, then the area (in ${\mathrm{cm}}^2$) of the semicircle will be ( Take $\pi =\frac{22}{7}$)