Revision Notes

5.1.2 Area - Adding & Subtracting

What do we mean by an awkward shape (a compund shape)?

  • Sometimes the shape we want to find the area of isn’t one of the standard shapes in Area – Formulae
  • However, the area may be found by using a combination of standard shapes
  • These are often called Compound Shapes and you may see Compound Area mentioned too

Finding the area of an awkward shape (compound area)

  • When you are asked to find the area of an “awkward” shape, split the shape into standard shapes first, and then add them together

Exam Tip

Take a moment to think about how to split up the shape into the easiest shapes possible – there will probably be more than one way to do it!

Occasionally it may be easier to add an extra shape to the diagram and subtract the area of the extra shape from the new bigger shape.

For example, for this shape you might complete the rectangle by putting a triangle in the top left corner. Then the area of the whole shape is the rectangle minus the triangle:

IGCSE & GCSE Maths revision notes

Worked Example

Area-of-Irregular-Pentagon, IGCSE & GCSE Maths revision notes

Area – Adding & Subtracting Example 2, IGCSE & GCSE Maths revision notes


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