Decoding Math Terms: POLY-, -GON, -HEDRON, EQUI-

Use Greek and Latin parts to decode geometry vocabulary.

Geometry names are almost all built from word parts. 'Poly-' means many. '-gon' comes from a Greek word for angle or corner. So a polygon is a shape with many angles. Number prefixes tell you how many: a pentagon has five angles (penta), a hexagon six (hexa), an octagon eight (octa). '-hedron' comes from a Greek word for seat or base, and in geometry means face: a polyhedron is a solid with many flat faces; a tetrahedron has four (tetra).

'Equi-' is Latin for equal: an equilateral triangle has equal sides (lateral means side), and equidistant means the same distance away. 'Quadri-' and 'quad-' mean four in Latin: a quadrilateral has four sides. Read: 'A cube is a regular hexahedron. ' Hexa (six) + hedron (face): six faces, which is exactly what a cube has. Word parts turn geometry vocabulary from memorization into translation.

• 1POLY- means many; -GON means angle.
• 2-HEDRON means face (of a solid).
• 3EQUI- means equal; LATERAL means side.