Area of a composite figure is the total region covered, found by partitioning a polygon into nonoverlapping rectangles, triangles, or other familiar figures, calculating each area from given or inferred dimensions, and adding the results; subtracting the area of a missing portion is an equivalent strategy. The result is expressed in square units, and the reasoning distinguishes area from perimeter while supporting later work with polygon area, scale, and algebraic expressions; curved boundaries and general formulas for arbitrary shapes are not included.
To find the area of a composite figure, split it into familiar shapes, find each area, and add them. You can also find the area of a larger shape and subtract a missing part.
Example: An L-shaped figure fits inside a rectangle that is units wide and units tall. The top-right corner is missing. The missing rectangle is units wide and units tall. Find the area of the L-shaped figure.
Find the area of the large rectangle:
Find the area of the missing rectangle:
Subtract the missing area from the large rectangle’s area:
The area of the L-shaped figure is
Remember, area measures the space inside a figure and is written in square units. Perimeter measures the distance around the outside, so it is a different measurement.
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