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。
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。
应用推荐