We are given some similar triangles. Their areas are , and . If the smallest triangle has a perimeter of 4, what is the sum of all the triangles' perimeters?
Solution
Because the triangles are all similar, they all have the same ratio of perimeter squared to area, or, equivalently, the same ratio of perimeter to the square root of area. Because the latter ratio is 4 for the smallest triangle, it is 4 for all the triangles, and thus their perimeters are , and the sum of these numbers is .
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