2007 Cyprus MO/Lyceum/Problem 25
Problem
A jeweller makes crosses, according to the pattern shown above. The crosses are made from golden cyclical discs, with diameter of 1cm each. The height of a cross, which is made from 402 such discs is
Solution
If represents the number of the cross, then there are disks in the cross ( to count for the 4 legs of the cross, plus one for the center and one for the bottom leg). So . The number of discs from top to bottom is .
See also
2007 Cyprus MO, Lyceum (Problems) | ||
Preceded by Problem 24 |
Followed by Problem 26 | |
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