Perimeter of flat figures

Perimeter is the measure of the contour of the flat geometric figures. In figures formed only by straight line segments, the perimeter is calculated from the sum of the measurements on all sides.

See below how to calculate the perimeter of flat figures.

Perimeter of flat figures

At flat figures they differ in terms of shape and number of sides and their measurements. Therefore, although the perimeter is always the measure of the contour, the way to calculate it can vary between the figures.

But don't worry, for the most common flat figures, there are formulas for calculating the perimeter. Check out!

perimeter of square

A square is a polygon with four equal sides, meaning they are all the same size. So, the perimeter of square is obtained by multiplying the side measurement by 4.

$\dpi{120} \mathbf{P = 4L}$

$\dpi{120} \mathbf{L}$ : measure from the side of the square.

rectangle perimeter

O rectangle it is a four-sided polygon, but only the opposite sides have the same measurement. O rectangle perimeter is obtained by the following formula:

$\dpi{120} \mathbf{P = 2\cdot (b+h)}$

On what:

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B: measure from the base of the rectangle;
H: rectangle height.

Triangle Perimeter

A triangle is a three-sided polygon, which can have the same or different measurements. Generally speaking, the triangle perimeter is obtained by adding the three measurements of the sides.

$\dpi{120} \mathbf{P = a+ b+c}$

The, B and ç: measurements from the sides of the triangle.

if the triangle is equilateral, that is, all sides equal the perimeter is obtained by multiplying the measure of the side by 3.

Perimeter of the trapeze

The trapeze is a four-sided polygon, with two sides being parallel and two sides not being parallel. The parallel sides are called bases, one larger and one smaller.

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O trapeze perimeter is calculated from the formula below:

$\dpi{120} \mathbf{P = B + b + l_1 + l_2}$

On what:

B: measure of the largest base;
B: measure of the smallest base;
$\dpi{120} \mathrm{\mathbf{l_1}\, and\, \, \mathbf{l_2}}$ : non-parallel side measurements.

Diamond Perimeter

O diamond is a polygon with four equal sides and the perimeter formula is the same as the square:

$\dpi{120} \mathbf{P = 4L}$

$\dpi{120} \mathbf{L}$ : measured from the side of the diamond.

It is noteworthy that the difference between square and diamond is in the measure of the internal angles. In the square, all the internal angles measure exactly 90°, whereas in the diamond, no.

circle perimeter

The circle is a flat figure classified as non-polygon, as it is not formed by straight segments. So your perimeter is calculated in a different way.

The formula of circle perimeter é:

$\dpi{120} \mathbf{P = 2 \boldsymbol{\pi} r}$