Find the area and perimeter of sector of a circle whose central angle is $45°$ and the radius of the circle is $7 \mathrm{cm}$

Flowers are to be planted in the shaded portion which is shown by sectors of two concentric circles of radii $14 \mathrm{m}$ and $7 \mathrm{m}$. If the area of the shaded region is $k {\mathrm{m}}^2$, then find the value of $k$.  $\left(\pi =\frac{22}{7}\right)$

The radius of a circle is $28 \mathrm{cm}$ and the area of the sector is $205.4 {\mathrm{cm}}^2$. If the central angle is $k°$ then find $k$ considering $\pi =\frac{22}{7}$.   [Write the value of $k$ only up to the decimal point]

An umbrella has $8$ ribs which are equally spaced. Assuming umbrella to be a flat circle of radius $45 \mathrm{cm}$. If the area between the two consecutive ribs of the umbrella is $k {\mathrm{cm}}^2$ then find $k$, correct upto one decimal place. [Assume $\mathrm{\pi }=\frac{22}{7}$]

The area of an equilateral triangle is $100\sqrt{3} {\mathrm{cm}}^2.$ Taking each vertex as the Centre, a circle is described with a radius equal to half the length of the side of the triangle, as shown in the figure. If the area of that part of the triangle which is not included in the circle is $k {\mathrm{cm}}^2$, then find $k$. (Take $\pi =3.14\text{ and }\sqrt{3}=1.732)$