Well, the ratio is 21/18 or 7/6 (you could take them the other way too) The lengths you'd find using the same logic. Corresponding to 12 there is 14, while for 14 there is somewhere around 16.33. The perimeter of the smaller is 14+18+12=44, while for the larger it is around 51.33. The ratio of the perimeter is the same as the ratio of lengths.
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The ratio of similitude between the two triangles is 7/6. The lengths of the other two sides of the larger triangle are approximately 16.33 meters and 14 meters, and their perimeters are 44 meters and 51.33 meters respectively. The ratio of the perimeters is equal to the ratio of the lengths of the sides of the triangles.
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