Perimeter of regular hexagon inscribed in a circle: If a regular hexagon is inscribed in a circle of radius r, what is its perimeter?
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A3r
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B6r
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C9r
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D12r
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E6πr
Answer
Correct Answer: 6r
Explanation
Introduction / Context:In a regular hexagon inscribed in a circle, each side equals the circle’s radius. This geometric fact allows a fast perimeter computation without trigonometry.
Given Data / Assumptions:
- Regular hexagon with 6 equal sides
- Inscribed in a circle (circumradius = r)
Concept / Approach:Each central angle is 360/6 = 60 degrees, making each chord equal to the radius. Therefore, side length s = r and perimeter P = 6s = 6r.
Step-by-Step Solution:s = rP = 6 * s = 6r
Verification / Alternative check:Construct equilateral triangles by joining the center to adjacent vertices; each has side r, confirming the chord length equals r.
Why Other Options Are Wrong:3r, 9r, and 12r are incorrect multiples; 6πr confuses polygon perimeter with a circle’s circumference formula.
Common Pitfalls:Assuming perimeter equals circumference; forgetting the chord property for regular hexagons.
Final Answer:6r