Step-by-step solution
Each shaded triangle above \(XY\) must have a mirror image below \(XY\) (and vice versa); shade the two missing mirror triangles.
Answer: see figure, shade the two triangles that mirror the existing shaded ones across XY
The answer
see figure, shade the two triangles that mirror the existing shaded ones across XY
PSLE 2014 Paper 1 Question 20 · Verified worked solution by the Genius Plus Academy teaching team
What this question tests
This is Question 20 of the PSLE 2014 Paper 1 Mathematics paper. It tests symmetry, in the Measurement & Geometry strand. It is worth 1 mark. Open your copy of the paper at this question, then follow our full worked solution below.
Each shaded triangle above \(XY\) must have a mirror image below \(XY\) (and vice versa); shade the two missing mirror triangles.
Answer: see figure, shade the two triangles that mirror the existing shaded ones across XY
Same structure, different costume
Change egg tarts to badges, a tank to two tanks, a ring of card to a folded sheet, and a child sees a brand new problem. The lock underneath is the same, and so is the key. Once a student can name the structure, a whole row of questions that look different start to open the same way.
It is also where marks really leak. Across fourteen years of papers, the marks lost in PSLE math leak at the reading far more than at the arithmetic, which is exactly why recognising the structure fixes them. We call this Lock and Key: name the lock, then the key follows.
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Same skill, different years. Each has a verified worked solution.
One of the 10 question types
The PSLE keeps testing the same 10 structures. Our PSLE Math Intensive trains the Lock and Key reflex across all ten, with 158 curated questions over two days.
It is a symmetry question from the Measurement & Geometry strand, worth 1 mark.
Not yet for this question. The full written solution is above, and we are filming Paper 2 walkthroughs steadily.
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