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jmc

geometry senior

Problem

With all angles measured in degrees, the product , where and are integers greater than 1. Find .
Solution
Let . Then from the identitywe deduce that (taking absolute values and noticing )But because is the reciprocal of and because , if we let our product be thenbecause is positive in the first and second quadrants. Now, notice that are the roots of Hence, we can write , and soIt is easy to see that and that our answer is .
Final answer
91