The method to find the perimeter of a polygon depends on whether it's a regular or irregular polygon.
Regular Polygons
A regular polygon has all sides of equal length and all angles of equal measure. To find its perimeter, you can use a simple formula:
Perimeter = Number of Sides × Length of One Side
For example, if you have a regular pentagon (5 sides) where each side is 5 cm long, the perimeter would be:
Perimeter = 5 sides × 5 cm/side = 25 cm
Irregular Polygons
An irregular polygon has sides of different lengths. To find its perimeter, you need to add up the lengths of all its sides:
Perimeter = Sum of the Lengths of All Sides
For example, if an irregular quadrilateral has sides of length 3 cm, 4 cm, 5 cm, and 6 cm, the perimeter would be:
Perimeter = 3 cm + 4 cm + 5 cm + 6 cm = 18 cm
In summary:
| Polygon Type | Method | Formula |
|---|---|---|
| Regular | Multiply side length by the number of sides | Perimeter = n × s (n=sides, s=side length) |
| Irregular | Add up the lengths of all sides | Perimeter = s1 + s2 + s3 + ... + sn |
