The circumference of a circle of diameter $7 \mathrm{cm}$ is

In the Fig., sides of a square are surrounded by four same semicircles each of radius  $10.5\mathrm{cm}$.The perimeter of the region so formed is                                        

In the Fig., an equilateral triangle-shaped wire is rebent to form a circular ring,  use $\left(\mathrm{\pi }=3.14\right)$. The radius of the ring so formed is