S K Gupta and Anubhuti Gangal Solutions for Chapter: Area of a Trapezium, a Polygon and Semicircle, Exercise 3: Exercise 21(B)

A school crossing sign has the dimensions as shown in the given figure.

If $4$ such sign boards are cut from the rectangular metal sheet $350 \mathrm{cm}$ long and $320 \mathrm{cm}$ wide, what will be the area of the metal leftover?

Find the area of a semicircle, when the area of the circle is $1476 {\mathrm{cm}}^2$.

Find the area of a semicircle (in ${\mathrm{cm}}^2$), when diameter of circle is $70 \mathrm{cm}$.

Find the radius( in $\mathrm{cm}$) of a semicircle whose area is $693 {\mathrm{cm}}^2$. (use $\mathrm{\pi }=\frac{22}{7}$ )

Find the diameter of a semicircle (in $\mathrm{cm}$) whose area is $100.48 {\mathrm{cm}}^2$ (use $\mathrm{\pi }=3.14$ ).
 

The area of two semicircles are in the ratio $49: 25$. Find the ratio of their circumferences.

The area of the given figure is 

The given figure is composed of four congruent trapeziums arranged around a shaded square. What is the area of the shaded square?