It’s not a perfect triangle but that wasn’t necessary. The three vertices of the outline of Sicily were enough to convince the pragmatic Romans to call it Trinacria (triangular). Although it would be the Greeks who dubbed it Sikelia (after the native tribes that lived there, the Sicels), which would morph into the present name of Sicilia, whose capital is Palermo.
It may not be evident in its name, but the number three still has a special relation with Sicily. This can be seen in its flag and its coat of arms, which is formed by three human legs supporting the head of Medusa.
According to legend, each one of those three extremities belongs to a different nymph: they travelled the world collecting the most beautiful things they found in each place. When swimming through the Mediterranean they were attracted to the crystalline waters at one point. They liked that stretch of sea so much that they decided to throw some fruit there. Each one left hers in a different place, forming a triangle. From that geometric shape there suddenly appeared an island that contained all the beautiful things the nymphs had harvested in their travels through the planet. Sicily sprung from and was supported by the number three.