Part 05 · Angles and area · Card 4 of 8
Area of 2D shapes
The amount of flat space inside a shape, measured in square units.
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Analogy
Like counting how many square tiles it takes to cover a floor.
Example
Trapezium area
Formula: 1/2 x (a + b) x ha = 6, b = 10, h = 4= 1/2 x 16 x 4 = 32 square units
In practice
Painters work out wall areas to know how many tins of paint to buy.
Practice
Flashcards
- What is the area of a trapezium with parallel sides 6 and 10, height 4?32. Use 1/2 x (6 + 10) x 4.
Questions people ask
What is the area of a triangle?
Half the base times the perpendicular height: area = 1/2 x b x h. The height must be measured at a right angle to the base, not along a slanted side. A triangle with base 8 and height 5 has area 1/2 x 8 x 5 = 20.
Why are areas measured in square units?
Area counts how many squares of a standard size fit inside a shape. So the units are squared: square centimetres (cm^2) or square metres (m^2). A room 4 m by 3 m has an area of 12 m^2, not 12 m.