The area of a circle is $75.46\, cm^{2}$. Find its circumference. (in $cm$)

In the figure,$AB$ is a diameter of the circle,$AC = 6 \, cm$ and $BC = 8 \, cm$. Find the area of the shaded region (Use $\pi = 3.14$). (in $cm^2$)

The union of a chord of a circle and its corresponding arc is called $\ldots \ldots \ldots \ldots$

$A$ cow is tied with a rope of length $14 \, m$ at the corner of a rectangular field of dimensions $20 \, m \times 16 \, m$. Find the area of the field in which the cow can graze. (in $m^2$)

The ratio of radii of two circles is $2:3$ and the ratio of the angles at the centre of two minor sectors of those circles is $5:2$. Then,the ratio of the areas of those sectors is:

If the radius of a circle is doubled,its area becomes $\ldots \ldots \ldots$ times the area of the original circle.