The circumference of a circle exceeds the diameter by $21 cm$. Find the area of the circle.

(Use $\mathrm{\pi }=\frac{22}{7}$)

The area of a circle is $1386 c{m}^2$; find its circumference.

(Use $\mathrm{\pi }=\frac{22}{7}$)

The difference between the perimeter and the radius of a circle is $37 cm$. Find the area of the circle.

(Use $\mathrm{\pi }=\frac{22}{7}$)

In Figure, $OABC$ is a rhombus, three of whose vertices lie on a circle with centre $O$. If the area of the rhombus is $18\sqrt{3} c{m}^2$, find the perimeter and area of the circle [take $\mathrm{\pi }=3.14$].

If the areas of two concentric circles are $154 c{m}^2$ and $616 c{m}^2$ respectively, then find the width and area of the circular path between them.

(Take $\mathrm{\pi }=\frac{22}{7}$)

Find the area of the largest circle that can be drawn inside a square of side $21 cm$.

(Take $\mathrm{\pi }=\frac{22}{7}$)