Area of an Equilateral Triangle (side = 8 cm): Find the area (in cm^2) of an equilateral triangle whose side length is 8 cm.

Difficulty: Easy

Correct Answer: 16√3 cm2

Explanation:


Introduction / Context:
The area of an equilateral triangle can be computed directly from side length using a fixed constant multiplier. This avoids trigonometric detours and emphasizes formula recall and clean substitution with units carried consistently.



Given Data / Assumptions:

  • Side a = 8 cm
  • Area formula: A = (√3/4) * a^2
  • All lengths in centimetres


Concept / Approach:
Substitute a = 8 into A = (√3/4)a^2. Since a^2 = 64, the product streamlines neatly. Reporting the exact radical form (rather than decimals) keeps precision and matches typical aptitude answer formats.



Step-by-Step Solution:

Compute a^2: 8^2 = 64.Apply formula: A = (√3/4) * 64 = 16√3 cm^2.Approximate (optional): √3 ≈ 1.732 ⇒ A ≈ 27.712 cm^2.


Verification / Alternative check:

Using height h = (√3/2)a = 4√3 ⇒ A = (1/2)*base*height = (1/2)*8*(4√3) = 16√3 cm^2.


Why Other Options Are Wrong:

  • 64 cm^2 is the square area, not the triangle's.
  • 4√3 cm^2 corresponds to side 4 cm.
  • 21.3 cm^2 is an inaccurate decimal; exact is 27.7…
  • 32√3 cm^2 doubles the correct value.


Common Pitfalls:

  • Using (1/2)ab with a wrong height; ensure equilateral height is (√3/2)a.


Final Answer:
16√3 cm2.

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