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Folding angle — find x
Gizelle has a rectangular piece of paper. She folded it along the dotted line (the diagonal, from the top-left corner to the bottom-right corner) as shown. At the bottom-right corner, the angle between the right-hand edge of the paper and the folded-over edge is 38 degrees, and x is the angle between that folded edge and the crease. Find angle x.
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65 worked examples are free without a code, two from every pattern. No account, either way.
The pattern behind it: Seeing it move
Work out where the pieces land after a fold, cut or stack.
In this one. A fold is a reflection in the crease, so the crease bisects the angle between an edge and its folded image — the angle a folding edge makes with the crease survives the fold unchanged.
How to spot it
Words like 'folded', 'cut along the dotted line' or 'stacked' appear beside a shape, and the question asks for a length or angle that only makes sense once the pieces are in their new positions.
Common mistake
Children try to calculate the answer before working out where the pieces actually end up, skipping the visualisation step that the whole question depends on.
Try one like it
Challenging Canvas — cut into a square and eight triangles Ravi has a square piece of canvas of side 31 cm. He cuts along the dotted lines to get one small square of area 289 cm² and 8 iden…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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