From (2) (3) we find by elementary algebra
u1/p2 = - u2/p1 = (u1 - u2)/(p1 + p2) = (u1 - u2)/P,
and therefore
p2u1 = - p2u2 = p1p2(u1 - u2)/P = k1k2[rho]1[rho]2(u1 - u2)/P
Encyclopaedia Britannica, 11th Edition, "Diameter" to "Dinarchus" Volume 8, Slice 4 · 第 81 / 86 题