1985 AMC 12 Problem 28
Attempt Problem 28 of the 1985 AMC 12 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1985 AMC 12 solutions, or check the answer key.
All problems are used with official legal permission of the Mathematical Association of America (MAA).
28.
In we have and What is
not uniquely determined
Answer: B
Small hint:
Use the sine law to write
Big hint:
After finding use and
Solution:
By the sine law and the triple-angle identity, Hence Since and therefore Also so another application of the sine law gives Thus the correct answer is B.
Problem 28 in other years
- 1950 AMC 12
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