EXERCISE 11.2

The side of an equilateral triangle is shown by $l$. Express the perimeter of the equilateral triangle using $l.$

The side of a regular hexagon is denoted by $l.$ Express the perimeter of the hexagon using $l.$

A cube is a three-dimensional figure as shown in Fig. It has six faces and all of them are identical squares. The length of an edge of the cube is given by $l$. Find the formula for the total length of the edges of a cube.

The diameter of a circle is a line which joins two points on the circle and also passes through the centre of the circle. (In the below figure $\mathrm{AB}$ is a diameter of the circle; $\mathrm{C}$ is its centre). Express the diameter of the circle ($d$) in terms of its radius ($r$).