Class 11 Maths Introduction To 3D Geometry | Coordinate Axes and Coordinate Planes |

**Coordinate Axes and Coordinate Planes in Three Dimensional Space**

Consider three planes intersecting at a point O such that these three planes are mutually perpendicular to each other. These three planes intersect along the lines X, Y & Z , called the x, y and z-axes, respectively. We may note that these lines are mutually perpendicular to each other. These lines constitute the rectangular coordinate system. The planes XOY, YOZ and ZOX, called, respectively the XY-plane, YZ-plane and the ZX-plane, are known as the three coordinate planes. The point O is called the origin of the coordinate system. The three coordinate planes. These three coordinate planes divide the space into eight parts known as octants.

**Note**: By convention, we take the XOY plane as the plane of the paper and the line Z′OZ as perpendicular to the plane XOY.

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