How Many Straight Lines?
Geometry
Level
3
How many straight lines are there that connect the centers of
circles?
28
25
29
27
26
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A simple trick that you can use while solving this problem is that the figure given has five axes of symmetry. They divide the figure into five identical smaller pieces, even if you have drawn the lines that connect the center of four circles. If the number of those lines is not divisible by 5, then the five pieces divided by those axes of symmetry would not be identical. Therefore, the answer must be divisible by 5. Since 25 is the only answer which satisfies this condition, it is obviously the correct answer.