c � 3 2 2 3 GRS80 1. OR 2 2 2 3 2 1 6,370 km 2 2 466–8673 18 φ1 λ1 φ2 λ2 L[km] L= 6370 arccos(sin φ1 sin φ2 + cos φ1 cos φ2 cos(λ1 − λ2)) (1) 2 2 3 2 3 2 1 3 2. 1 (1) (1) [1] 1 O 1 3 3 3 1 A, B, C a, b, c 2015 12 Copyright c � by ORSJ. Unauthorized reproduction of this article is prohibited. 11 701 1 ABC 2 AB� C� 2 (1) ⎧ ⎪ ⎪ ⎨ ⎪ ⎪ ⎩ cos a = cos b cos c + sin b sin c cos A cos b = cos c cos a + sin