Find the area of the shaded region:

_____ is the distance around a closed figure.

The distance around a circular region is called its _____.

If the area of a square is $64 {\mathrm{cm}}^2$, then its perimeter is _____.

If the side of a square is doubled, then its perimeter becomes _____ times the original perimeter.

If both the height and base of a triangle are halved, then its area becomes _____ times the original area. (half/one-fourth/one-third)

If the circumference of a circle is $154$ $\mathrm{cm}$, then its radius is _____ $\mathrm{cm}$.

If the area of a circle is $314 {\mathrm{m}}^2$, then its diameter is_____ $\mathrm{m}$. (Use $\pi =3.14$)