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Find sin4(π/45) + sin4(2π/45) + ... + sin4(89π/45).
(No Solution Yet, 1 Comments) Submitted on 2025-05-02 by Danish Ahmed Khan   
Difficulty: 3 of 5 Bonus: Prime Perimeter (in Logic) Rating: 2.82

You and two other people have numbers written on your foreheads. You are all told that the three numbers are primes and that they form the sides of a triangle with a prime perimeter. You see 5 and 7 on the other two heads and both of the other people agree that they cannot deduce the number on their own foreheads.

What is the number written on your forehead?

(Solution Posted, 90 Comments) Submitted on 2005-03-11 by Erik O.   
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