Area - Quadrilaterals
(and other polygons)
To find the area of some polygons we can either treat them as
composite shapes, ie several smaller shapes stuck together, or draw
a rectangle round the whole structure and remove the external triangles.
Which method is better will depend on how you are given the
dimensions of the shape.
For this shape we can find the area of all the small blue triangles and
subtract them from the large rectangle.
area = 8 x 4 - (2x2÷2 + 6x1÷2 + 3x3÷2 + 5x2÷2) = 32 - 14.5 = 17.5 cm²
Now you need to practise:
downloadable worksheet
(save this file then run it)