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Parallelogram BCDE — find ∠EAB
EAD is a triangle and BCDE is a parallelogram, with AB = BE. Given ∠DBC = 39° and ∠BCD = 73°, find ∠EAB.
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The pattern behind it: Angle chasing
One angle gives you the next, until you reach the angle asked for.
In this one. B sits on the straight line AD, so the parallelogram angle left over at B (∠EBD = 68°) is the exterior angle of the isosceles triangle ABE — it equals the two equal base angles added together, so ∠EAB is just half of it.
How to spot it
A figure has several angles marked with only one or two values given, and words like 'isosceles', 'parallel', or 'straight line' point to which rule to use first.
Common mistake
Children apply an angle rule to the wrong triangle or the wrong straight line in a crowded figure, or stop one step before the angle actually asked for.
Try one like it
Challenging A display easel — angle EAB A framer is building a triangular display easel EAD, braced by a parallelogram strut BCDE, where B lies on strut AD. The two strut…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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