In 3-dimensional geometry, a plane of symmetry is a 2-dimensional flat dividing surface placed such that things on one side are symmetrical (mirror image) to things on the other side.
... the village the population is spread out with 20.5% under the age of 18, 6.1% from 18 to 24, 24.6% from 25 to 44, 28.2% from 45 to 64, and 20.7% who are 65 years of ...