SPHEROID

(Yunanca köken — orijinale bakınız.) In Geometry, a solid generated by the revolution of an ellipse about one of its axes. If the generating ellipse revolves about its major axis, the spheroid is prolate, or oblong; if about its minor axis, the spheroid is oblate. Let 2 a be the axis of revolution, and 2 b the diameter of the generating ellipse perpendicular to the axis; then the origin of the co-ordinates being at the centre, and x being taken on the semi-axis a, the equation of the surface of the spheroid is [s. 1151]