Chapters

## Perimeter

The perimeter of a polygon is equal to the sum of the length of its sides.

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## Area

The area of a polygon is the measure of the region enclosed by the sides of a polygon.

## Perimeter of a Triangle

 Equilateral Triangle Isosceles Triangle Scalene Triangle

## Example

Find the area and perimeter of the following triangle:

P = 2 · 11 + 7.5 = 29.5 cm

## Example

Calculate the area and perimeter of a square with 5 cm sides.

A = 5² = 25 cm²

## Example

Calculate the area and perimeter of a rectangular with a base of 10 cm and a height of 6 cm.

P = 2 · (10 + 6) = 32 cm

A = 10 · 6 = 60 cm²

## Example

Calculate the area and perimeter of a rhombus whose diagonals are 30 and 16 cm, and its side measures 17 cm.

P = 4 · 17 = 68 cm

P = 2 · (a + b)

A = b · h

## Example

Calculate the area and perimeter of a rhomboid shape of 4 sides of 4.5 cm and a height of 4 cm.

P = 2 · (4.5 + 4) = 17 cm

A = 4 · 4 = 16 cm²

## Example

Calculate the area of the following trapezoid:

### Area of a Regular Polygon

n is the number of sides

Calculate the area and perimeter of a regular pentagon with sides of 6 cm.

By applying the Pythagorean theorem for one of the triangles, we obtain:

Calculate the area and perimeter of a regular hexagon inscribed in a circle of 4 cm radius.

P = 6 · 4 = 24 cm

### Area of a Polygon

The area is obtained by triangulating the polygon and adding the area of these triangles.

A = T1 + T2 + T3 + T4

Calculate the area of the following polygon:

P = 11 · 2 + 5 + 13 + 12 = 52 cm

AD = BC; AB = DC Rhomboid

A = AR + AT

A = 11 · 12 + (12 · 5 ) : 2 = 162 cm²

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