Answer:
D. 37.947
Explanation:
Heron's formula makes use of the value "s", the semi-perimeter. Here, ...
s = (7 + 11 + 12)/2 = 15
Then the area is ...
A = √(s(s -a)(s -b)(s -c)) = √(15·3·4·8) = √1440 = 12√10 ≈ 37.947
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Comment on answer choices
This value is verified by a triangle solver. We suspect a typographical error in the answer choices, specifically, selection D.