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
Topic
Shape, Area and Perimeter
Area measures the space inside a flat shape. It is used for floors, walls, fields, and tiles.
Topic explanation
Area is measured in square units such as cm² or m² because it counts squares covering a surface.
For triangles, use the base and the straight height. Then divide by 2.
Compound shapes become easier when you split them into rectangles first.
Quick methods
- Rectangle
- Area = length × width
- Triangle
- Area = base × height divided by 2
- Units
- Area answers use square units such as cm² or m²
- Compound shapes
- Split into rectangles first, then add the areas.
Worked examples
Example 2
Find the area of a triangle with base 10 cm and height 6 cm.
- For a triangle, area = base × height divided by 2.
- Multiply the base and height: 10 × 6 = 60
- Divide by 2: 60 divided by 2 = 30
So: The area is 30 cm².
Example 3
A shape is made from two rectangles. One is 6 m by 3 m. The other is 4 m by 2 m. Find the total area.
- Find the first rectangle area: 6 × 3 = 18 m².
- Find the second rectangle area: 4 × 2 = 8 m².
- Add the areas: 18 + 8 = 26
So: The total area is 26 m².