Sector of a Circle

Find the area of a circle whose radius is $2.1 m$.

The angle of a sector of a circle is $72°$ and radius of the circle is $10 \mathrm{m}$. The ratio of the circumference of the circle and the length of the arc of the sector is _____. 

The angle of a sector of radius $14 \mathrm{cm}$ is $90°$. The area of the sector is _____.

If the angle of a sector is $30°$ and the radius of the sector is $21 cm$, then the length of the arc of the sector is ____.

If the area of a sector of a circle is $\frac{1}{6}$ of area of the circle, then the angle of the sector is _____ in degrees.

The radius of a circular field is $105 \mathrm{m}$. The area obtained by a sector of angle $72°$ is used for paddy growing. The perimeter of the sector is _____.

The angle of a sector of a circle $90°$. The ratio of the area of the sector and that of the circle is _____.

The angle of a sector is $120°$ and its radius is $21 \mathrm{cm}$. The area of the sector is _____.

The angle of a sector of a circle is $108°$ and radius of the circle is $15 \mathrm{m}$. The ratio of the circumference of the circle and the length of the arc of the sector is _____.

The sector of a circle has radius of $21 \mathrm{cm}$ and central angle $135°$. Find its perimeter. [Take $\mathrm{\pi }=\frac{22}{7}$]