Finding the Area of Irregular Shapes

What are Irregular Shapes?

Irregular shapes are shapes that have sides and/or angles of different lengths and sizes, i.e. the sides are not all of equal length, and/or the interior angles are not all the same size.

Area of the Green Shape

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Area of the Blue Shape

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Area of the Orange Shape

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What did you notice about the three shapes? Is there are connection between their areas? *Use the tool below to help you answer this question*

Finding the area of Irregular Shapes

To find the area of irregular shapes, you will decompose the irregular shape into regular shapes, such as triangles or regular polygons, then find the area of each of the regular shapes and add them together. Some of the common regular shapes used when decomposing irregular shapes are rectangles, squares, triangles, circles or semicircles, and trapezoids.

Example

This irregular shape was split into two shapes, a rectangle (shape A) and a square (shape B). Find the area of the rectangle and the area of the square, and then add the two areas together.