P6 Circles and curved boundaries
composite perimeter — radius 14 cm
A 36 cm by 28 cm rectangle has a semicircle attached externally to each of its two opposite 28 cm sides. Find the outside perimeter. Use π = .
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The pattern behind it: Circles and curved boundaries
Find the space inside a circle shape or the distance around its boundary.
In this one. Trace only the outside boundary. The shared diameters are inside the shape, so they are not part of its perimeter.
How to spot it
'Area' asks for square centimetres from the radius. 'Circumference' or 'perimeter' on a curved edge asks for plain centimetres from the diameter instead.
Common mistake
Children give a circumference answer in square units, or find a circle's area without squaring the radius first, mixing up the two kinds of measurement.
Try one like it
Standard circle area — radius 14 cm A circle has radius 14 cm. Find its area. Use π = 22/7.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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