perimeter

Everyday

1. The perimeter is the length all the way around a shape. tree →
2. The perimeter of a place is its outer edge or border, like the fence around a field. tree →

In the lessons

In maths: the distance around a shape: fences, borders, frames; add all the sides. In everyday life: fencing a garden, putting a border on a picture or ribbon around a cake. In stories: guards walk around the perimeter of the castle.

Examples

• Find the perimeter of a square with 5 cm sides. tree →
• The perimeter of the garden is 40 meters. tree →
• How much fence is needed for the perimeter? tree →
• The rectangle has a perimeter of 30 cm. tree →
• We put a ribbon around the perimeter of the card. tree →
• The dog ran along the perimeter of the field. tree →
• A triangle with sides 3, 4 and 5 cm has a perimeter of 12 cm. tree →
• Guards patrolled the perimeter of the camp. tree →

Note

Add all the sides. Rectangle: 2 × (length + width); square: 4 × side. Trap: perimeter is not area; do not multiply length by width. Perimeter is a length, so its unit is cm or m, not square cm. The perimeter of a circle is called its circumference.