How are the eight quadrants of space divided?

In space solid geometry, the mutually perpendicular coordinate axes X, Y and Z can determine three mutually perpendicular planes, which are collectively called coordinate planes. The coordinate plane defined by X axis and Y axis is called xOy plane, and there are also yOz plane and zOx plane. Three coordinate planes can divide the space into eight parts.

Eight hexagrams use letters I, II, ... and VIII, in which the first hexagram contains the positive semi-axis of X axis, Y axis and Z axis, and the other three hexagrams on the xOy plane are arranged counterclockwise, followed by the second, third and fourth hexagrams. Below the xOy plane, the hexagram limit adjacent to the first hexagram limit is the fifth hexagram limit, and then it is also arranged counterclockwise as the sixth hexagram limit, the seventh hexagram limit and the eighth hexagram limit.

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In the plane rectangular coordinate system, four areas divided by horizontal axis and vertical axis are divided into four quadrants. The quadrant takes the origin as the center and the X axis and Y axis as the dividing line. The upper right is called the first quadrant, the upper left is called the second quadrant, the lower left is called the third quadrant, and the lower right is called the fourth quadrant. The points on the coordinate axis do not belong to any quadrant.

The first quadrant: (positive+,+positive), the abscissa and ordinate have the same sign, and it is denoted as xy>0;

The second quadrant: (negative-,+positive), which has different symbols in horizontal and vertical coordinates and is expressed as xy.

The third quadrant: (negative-,-negative), which has the same sign on the horizontal and vertical axes, and is expressed as xy>0;

The fourth quadrant: (positive+,-negative), the abscissa and ordinate have different signs, and it is denoted as xy.

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