Difficulty: Medium
Correct Answer: 98.5 sq. cm
Explanation:
Introduction / Context:
The “remaining portion” means triangle area minus the area of the incircle. For an equilateral triangle, the inradius has a simple formula in terms of side length, which makes computation straightforward and exact in radicals; the options here are rounded decimal values.
Given Data / Assumptions:
Concept / Approach:
Compute the triangle’s area and the incircle’s area, then subtract. Use either π = 22/7 or π ≈ 3.1416 for the circle; the rounded answer must match given options. Using standard exact expressions first helps consistency.
Step-by-Step Solution:
Verification / Alternative check:
Using π = 22/7 gives 48*(22/7) ≈ 150.86, still leading to ~98.55 cm². The closest option is 98.5 sq. cm.
Why Other Options Are Wrong:
36.6, 54.2, 72.8 are far from the precise subtraction.
Common Pitfalls:
Mistaking circumradius for inradius; forgetting that incircle area uses r, not R.
Final Answer:
98.5 sq. cm
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