As to Model 1,we work out the spherical distance in solid geometry,it turns out that it only costs 10 8734 hours to fly from Beijing to Detroit,while 14 7793 hours by the original flight course,and at least 3 9095 hours is saved.

• 对于模型 1；采用立体几何知识求球面距离的方法 ；得出从北京直接到底特律的时间为 10 8734h ；而按飞机的原航线则至少需14 7793h ；所以至少节省时间为 3 90 5 9h .