Perimeter and A...

Find the area of a ring whose outer and inner radii are $19\ cm$ and $16\ cm$ respectively.

The circumference of a circular field is $308 m$. Find its radius in metres.

The total boundary length of circle is called 

Find the missing length of the following figure.

Find the missing length of the figure given below.

A circle is inscribed in a square as shown below. If the radius of the circle is $4$ cm, then the perimeter of the square is ______

Perimeter of a circle is called as__________

Perimeter of a circle is called as

Perimeter of a circle is called its

The radius of a wheel is $0.25 m$. How many rounds will it take to complete the distance of $11 km$?