👉 In mathematics, a zonated surface is a two-dimensional surface that is bounded by an infinite number of lines. These lines are called the meridians and parallels of the zonoid. The zonoids are named after their position in relation to the equator or poles. For example, consider the zonoid defined by the equations: x^2 + y^2 = 1 y = x This surface is bounded by a single line parallel to the x-axis at