20/07/13 21:39:24 nRP7fpY9.net
>>143
・座標
O (0, 0, 0)
A (1, 0, 0)
B (1, 2x/(1-xx), 0)
C (0, 0, 2y/(1-yy))
・稜長
OA = 1, OB = (1+xx)/(1-xx), OC = 2y/(1-yy),
AB = 2x/(1-xx), AC = (1+yy)/(1-yy), BC = z,
・面積
OA⊥AB より ?OAB = OA･AB/2 = x/(1-xx),
OA⊥OC より ?AOC = OA･OC/2 = y/(1-yy),
OB⊥OC より ?BOC = OB･OC /2 = (1+xx)y/{(1-xx)(1-yy)},
AB⊥AC より ?BAC = AB･AC /2 = x(1+yy)/{(1-xx)(1-yy)},
・体積
V(COAB) = OC･OA･AB /6 = 2xy/{3(1-xx)(1-yy)},