(geometry) base / bottom of the lower class

centimetre

centimetre

cubic centimeter (US), cubic centimetre (UK) - a unit of volume equal to that of a cube having sides each one centimeter in length, commonly used in fluid measure and for engine sizes. Symbols: cm³ and cc

October

a unit of area (1cm × 1cm), symbol cm², (UK) square centimetre, (US) square centimeter.

a triangle (polygon)

a right-angled triangle

a tridecagon

acute triangle (triangle all of the angles of which are acute)