Perimeter and Area
"Calculate perimeter of polygons and area of squares and rectangles on square grids."
A Today you'll learn
- Understand perimeter as the total distance around the outer boundary of a closed shape
- Understand area as the surface space enclosed inside a boundary measured in square units
- Calculate perimeter and area of rectangles and squares using formulas
B Let's understand
Perimeter and area are two essential measurements of 2D shapes. The perimeter is the total length of the boundary around a closed figure. Think of perimeter as the length of fence you need to build around a playground. To find perimeter, add up the lengths of all its sides: Perimeter of rectangle = 2 × (Length + Breadth); Perimeter of square = 4 × Side. Area, on the other hand, is the amount of surface space covered inside the boundary, like the carpet covering a floor. Area is measured in square units (sq cm or sq m): Area of rectangle = Length × Breadth; Area of square = Side × Side.
C See it step by step
- Perimeter = 2 × (Length + Breadth) = 2 × (8 + 5) = 2 × 13 = 26 cm.
- Area = Length × Breadth = 8 cm × 5 cm = 40 sq cm (cm²).
- Perimeter = 4 × Side = 4 × 6 m = 24 metres.
- Area = Side × Side = 6 m × 6 m = 36 sq metres (m²).
D Your turn
E Ready to practise?
Key idea 1
Perimeter is the total boundary distance (measured in cm, m, km).
Key idea 2
Area is the total surface space covered inside (measured in cm², m²).
Key idea 3
Perimeter of a square = 4 × side; Area of a square = side × side.
Key idea 4
Perimeter of a rectangle = 2 × (length + breadth).
Area of a rectangle = length × breadth
Area of a rectangle = length × breadth.