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Printsmc
counting and probability senior
Problem
A set of points in the -plane is symmetric about the origin, both coordinate axes, and the line . If is in , what is the smallest number of points in ?
(A)
(B)
(C)
(D)
Solution
If is in , then is also, and quickly we see that every point of the form or must be in . Now note that these points satisfy all of the symmetry conditions. Thus the answer is .
Final answer
D