Read the abscissa in () first, then the ordinate. Just read "one, two" directly, with a pause in the middle. Coordinates, mathematical nouns. Refers to the spherical coordinate system established on the celestial sphere to determine the position of a point on the celestial sphere.

Basic elements of coordinates

① Basic plane; Determined by the great circle selected on the celestial sphere; The great circle is called the base circle, and one of the two geometric poles of the base circle is the pole of the spherical coordinate system.

2 points, also known as the origin; It is determined by the intersection of the great circle of the selected pole and the base circle in the coordinate system on the celestial sphere.

Plane coordinate system is divided into three categories.

Absolute coordinate: refers to the specific position of a point on the plane with point O as the origin and reference point, which is expressed as: A(X, y);

Relative coordinates: take the last point of a point as a reference point to locate the specific position of the point on the plane, which is expressed as: A(@△X, △ y);

Relative polar coordinates: refers to the displacement distance, direction and angle of a point on a plane relative to the previous point, which is specifically expressed as: a (@ d