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Two-dimensional shapes Area of composite shapes

Two-dimensional shapes are flat. The perimeter of a 2D shape is the total distance around the outside of the shape. The area of a 2D shape is the space inside the shape. Compound shapes can be split into different shapes to work out total area.

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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.

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  1. 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

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Area of compound shapes

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