Perimeter of Shapes
Calculate the perimeter of 2D shapes by adding the lengths of all sides.
What You Need to Know
Key Concept Diagram
Perimeter is the total distance around the outside of a 2D shape.
Add all side lengths to find the perimeter (P = sum of all sides).
Regular polygons have equal side lengths, so P = number of sides × side length.
Perimeter is measured in length units: mm, cm, m, or km.
Key Vocabulary
perimeter
The distance around the outside of a 2D shape.
polygon
A closed flat shape made of straight sides.
side length
The measurement of one straight edge of a shape.
regular
A shape where all sides and all angles are equal.
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
A rectangle has sides 5 cm and 3 cm. What is its perimeter?
Question 2
A regular hexagon has side length 4 cm. What is its perimeter?
Question 3
A triangle has sides 7 m, 9 m, and 6 m. What is its perimeter?
Key Concepts Summary
- ●Perimeter is the total distance around the outside of a 2D shape.
- ●Add all side lengths to find the perimeter (P = sum of all sides).
- ●Regular polygons have equal side lengths, so P = number of sides × side length.
- ●Perimeter is measured in length units: mm, cm, m, or km.