Recover Side Length from Area — Equilateral Triangle: The area of an equilateral triangle is 4√3 cm^2. Find the length of each side (in cm).
Aptitude
Area
Difficulty: Easy
Choose an option
-
A4/√3 cm
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B√3/4 cm
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C3 cm
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D4 cm
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E2√3 cm
Answer
Correct Answer: 4 cm
Explanation
Introduction / Context:Equilateral triangle area depends solely on side length via a constant factor. Inverting the standard formula lets us find side length directly from a given area, reinforcing comfort with algebraic manipulation and radicals.
Given Data / Assumptions:
- Area A = 4√3 cm^2
- Formula: A = (√3/4) * a^2
- a is the side length in cm
Concept / Approach:Set 4√3 = (√3/4) * a^2 and solve for a^2 by isolating it. Cancel √3 on both sides to simplify early and avoid handling nested radicals later. Take the positive square root because side length is positive.
Step-by-Step Solution:
4√3 = (√3/4) * a^2.Multiply both sides by 4/√3 ⇒ a^2 = 4√3 * (4/√3) = 16.Therefore, a = √16 = 4 cm.Verification / Alternative check:
Plug back: (√3/4)*4^2 = (√3/4)*16 = 4√3 cm^2, matching the given area.Why Other Options Are Wrong:
- 4/√3 cm and √3/4 cm misapply inversion steps.
- 3 cm does not satisfy (√3/4)*9 = 2.25√3.
- 2√3 cm gives area (√3/4)*12 ≈ 3√3, not 4√3.
Common Pitfalls:
- Forgetting to multiply by 4/√3 to isolate a^2.
- Taking the square root prematurely before simplifying constants.
Final Answer:4 cm.