Complex sentence: The Reuleaux triangle is the first of a sequence of Reuleaux polygons, curves of constant width formed from regular polygons with an odd number of sides, some of which have been used as the shapes of coins.
Split into simpler sentences: The Reuleaux triangle is the first of a sequence of Reuleaux polygons, curves of constant width formed from regular polygons with an odd number of sides. Some of these curves have been used as the shapes of coins.