在两条基线相交成直角的情况下，如果两条基线长度相等，则测最精度与基线的方位角无关；

When one baseline is kept to be perpendicular to another, if their lengths are equal, the accuracy does not vary with their azimuths;

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与每一子午线相交成同一角度的航向叫恒向线。

The course which will cut each meridian at the same angle is termed a rhumb line.

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