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Ai Tong 2025 P6 Maths Prelim — Paper 1 Booklet A Q13 Solution

Paper 1 Booklet A · Q13 · 2 marks · Area and Perimeter

Question

The figure is made up of two identical semicircles with radius of 21 m. Find the perimeter of the figure in terms of $\pi$.

1. 21$\pi$ m
2. (21$\pi$ + 21) m
3. 42$\pi$ m
4. (42$\pi$ + 42) m

Answer: 4

Worked solution

\text{Each semicircle arc} = \pi \times 21 = 21\pi \text{ m}
\text{Total arc length} = 2 \times 21\pi = 42\pi \text{ m}
\text{Straight edge (diameter)} = 2 \times 21 = 42 \text{ m}
\text{Perimeter} = (42\pi + 42) \text{ m}

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