If there is a line passing the top of the ruler, and parallel to the equator, then the Angle between the line and the ruler is equal to the latitude here.
如果有一条线和赤道线平行，而且经过尺的顶端，这条线和尺的夹角就等于纬度。
2
The utility model discloses a collapsible ruler, which is formed by the combination of two rulers glidingly assembled into integration; the two rulers face each other and are parallel mutually.