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?

Name the plane shape whose area is given by the area formula: 

$\mathrm{A}=\frac{1}{2}\mathrm{bh}$

Name the plane shape whose area is given by the area formula: 

$\mathrm{A}=\mathrm{bh}$

Name the plane shape whose area is given by the area formula: 

$\mathrm{A}=\frac{1}{2}\left({\mathrm{b}}_1+{\mathrm{b}}_2\right)\mathrm{h}$

Name the plane shape whose area is given by the area formula: 

$\mathrm{A}=\frac{1}{2}\times {\mathrm{d}}_1\times {\mathrm{d}}_2$