Example 1
Find the area of a rectangle 7 cm long and 4 cm wide.
- For a rectangle, area = length × width.
- Multiply 7 by 4.
- 7 × 4 = 28
So: The area is 28 cm².
Back to National 3
Unit: Shape, Space and Measures
Area and Perimeter
Area measures the space inside a flat shape. It is used for floors, walls, fields, and tiles.
Supports assessment standards: 1.1, 2.2
Topic explanation
Area is measured in square units such as cm² or m² because it counts squares covering a surface.
National 3 core work uses regular 2D shapes such as rectangles and squares. Triangle and compound-shape area are kept only in clearly labelled National 4 preparation.
Use the context to choose area or perimeter, then check whether the answer needs length units or square units.
Quick methods
- Rectangle
- Area = length × width
- Square
- Area = side × side
- Units
- Area answers use square units such as cm² or m²
- Choose the measure
- Boundary means perimeter; covering means area.
Worked examples
Example 2
Find the area of a square with side length 6 cm.
- For a square, area = side × side.
- Multiply 6 × 6 = 36
- Area uses square units.
So: The area is 36 cm².
Example 3
A rectangular garden is 8 m long and 5 m wide. How much fencing is needed around it?
- Fencing goes around the boundary, so find the perimeter.
- Add all four sides: 8 + 5 + 8 + 5.
- The total is 26.
So: The garden needs 26 m of fencing.