Co-ordinates, System of

A system for indicating the position of points in space by reference to fixed lines, intersecting at a determined and arbitrary point 0, termed the origin of co-ordinates. In plane rectangular co-ordinates two lines are drawn through the origin, one horizontal, termed the axis of absci as, or axis of X. All distances measured parallel to it, if unknown, are indicated by x, and are termed absci as. The other axis is vertical, and is termed the axis of ordinates, or axis of Y. All distances measured parallel to it, if unknown, are indicated by y and are termed ordinates. Thus by naming its absci a and ordinate a point has its position with reference to the axes determined, and by indicating the relation between a point, line or curve, and a system of absci as and ordinates, the properties of a line or curve can be expre ed algebraically. Co-ordinates may also be inclined to each other at any other angles, forming oblique co-ordinates; relations may be expre ed partly in angles referred to the origin as a centre, giving polar co-ordinates. For solid geometry or calculations in three dimensions, a third axis, or axis of Z, is used, distances parallel to which if unknown are indicated by z. IMG:8956969607833025625_151F112.jpg: Fig. 112. AXES OF CO-ORDINATES. 151   STANDARD ELECTRICAL DICTIONARY.