Task: Text Categorization
Input (English): Ceva's theorem deals with lines constructed in these polygons, and Apollonius' theorem also deals with these polygons. The Euler line of one of them passes through several significant points, including the center of the nine-point circle. Their area can be calculated using Heron's formula. A fractal named for Sierpinski is based on these polygons, which have centroids, orthocenters, and circumcenters. For 10 points, name these polygons which may be scalene or equilateral.
Output (English): Science