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Perimeter and area - WJECArea of composite shapes

Knowing how to find the perimeter or area of a shape can be useful in everyday life - from wrapping a present to buying a carpet. Use it in calculations to find the amount of materials needed or cost.

Part of Maths Numeracy (WJEC)Geometry and Measure

Area of composite shapes

To calculate the area of a composite shape you must divide the shape into rectangles, triangles or other shapes you can find the area of and then add the areas back together.

You may have to calculate missing lengths before finding the area of some of the shapes.

Image gallerySkip image gallerySlide 1 of 9, A composite shape with sides of various lengths. The lengths of four of the sides are unknown, Area of a compound shape Calculate the area of this compound shape.

Other composite shapes may have cut out sections. To work out the area of these shapes, you must calculate the area of the main shape and subtract the area of the cut-out.

Question

Calculate the area of the shaded shape.

A rectangle of width 20 mm and height 15 mm. Inside the rectangle is a cut-out section in the shape of a trapezium