●a=b=6378.140c=6356755 a-C e- a 300R=vac 4 球=zR扁=m2c300 1 = − = a a c e 3 3 4 V球 ＝ R V a c 2 3 4 扁 ＝  3 2 R = a c ⚫ a=b=6378.140 c=6356.755