Perimeter

The perimeter is measured in units of mm, cm, or meters, according to what the question states.
Generally, most figures are given in units of cm.
We can convert the different units of measure in the following way:
$1$ cm = $10$ mm
$1$ meter = $100$ cm

Now we will learn to calculate the perimeter of the most known figures. Are we ready?
How is the perimeter calculated in general?
All the lengths of the edges (or sides) of the figure are added together.
The sum of all the edges is the perimeter.

$a$ -> Side of the square
In the square, all sides are equal, therefore, its perimeter will be $4$ times the side $a$.
We will multiply the side of the square by $4$.

Let's add up the sides of the rectangle. The opposite sides are equal.

More information about the Perimeter of the rectangle

Let's add up all the sides of the triangle.
In an isosceles triangle it is enough to know the length of the base and one of the two equal sides.
In an equilateral triangle it is enough to know the length of one side.

More information about the Perimeter of the triangle

$a$ -> side of the rhombus
In the rhombus all sides are equal, therefore, its perimeter will be 4 times the side a.

Let's add up the sides of the parallelogram. The opposite sides are equal.

More information about the Perimeter of a parallelogram

$r$ –>  Radius of the circumference
Pi $π$ will be calculated as the number –> $3.14$

Let's multiply Pi –> $3.14$ by the radius by $2$

More information about the Circle's perimeter

Let's add up all the sides of the trapezoid

More information about the Perimeter of the trapezoid

In the deltoid, the 2 adjacent sides are equal.

The key to calculating the perimeter of these figures is to add up absolutely all the sides without forgetting any of them.
Start on one side, follow the entire round and stop when you reach the same side from which you started.

Let's see an example:

The area is:
$4+4+4+5+2+8+2+3=32$

The perimeter is measured in two-dimensional figures that do not have volume, for example, a rectangle

In contrast, the surface area is measured in three-dimensional figures that do have volume, for example, a cylinder or cube.