A brooch is crafted from silver wire in the shape of a circle with a diameter of 35 cm. The wire is also used to create 5 diameters, dividing the circle into 10 equal sectors as shown in figure.
Generated by claude-sonnet-4-6 · 2026-06-15 10:38 · grounding stimulus
Model Answer
(i) Radius of the circle:
Radius = Diameter ÷ 2 = 35 ÷ 2 = 17.5 cm
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(ii) Circumference of the brooch:
Circumference = 2πr = 2 × (22/7) × 17.5 = 110 cm
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(iii) Total length of silver wire required:
The wire forms:
- The circular boundary (circumference) = 110 cm
- 5 diameters = 5 × 35 = 175 cm
Total length = 110 + 175 = 285 cm
Source: Areas Related to Circles, Chapter 11
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Explanation
- Part (i) is direct: radius = d/2.
- Part (ii): Use 2πr with π = 22/7 (standard CBSE value unless stated otherwise).
- Part (iii) is the 2-mark part — examiners expect both components (circumference + 5 diameters) shown separately before adding. Missing either component loses a mark. Show working clearly.