P4 Rectangle and square measurement
perimeter of a composite rectilinear figure
A composite rectilinear figure is formed by removing a 2 cm by 2 cm corner from a 9 cm by 6 cm rectangle. Find its perimeter.
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The pattern behind it: Rectangle and square measurement
Use opposite equal sides, undo the area or perimeter formula, and count each outside edge once.
In this one. Trace only the outside boundary. The two new notch edges replace equal lengths removed from the original outer edges.
How to spot it
Squares tiling a rectangle, or a shape made of several rectangles joined together, point here. The question asks for area, perimeter, or the length of a missing side.
Common mistake
Children multiply length by width when the question actually asks for perimeter. On a composite shape, they add only the labelled sides and miss the ones they must work out themselves.
Try one like it
Standard find a rectangle side from area A rectangle has area 63 cm² and length 9 cm. Find its width.The 33 problem patterns
All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.
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