我国某学校地理兴趣小组采用“等长日影角平分线法”确定正北方向,并记录了日影与正北方重合的北京时间。具体方法为:第一天在地面画若干个同心圆(如右上图所示),测得标杆顶部投影点在同一圆周上的位置 Geographic interest group in a certain school in our country determined the direction of Zhengbei by adopting the method of bisector of equatorial diurnal angle of view and recorded the Beijing time when the shadow of Japan and the north coincide. The specific method is: the first day of drawing a number of concentric circles on the ground (as shown in the upper right), measure the position of the top of the benchmark projection point on the same circumference