in which

x12 + x22 = F2 − x32, x1y1 + x2y2 = FG − x3y3,

(5)

r (y12 + y22) = 2T − p(x12 + x22) − p′x32 − 2q (x1y1 + x2y2) − 2q′x3y3 − r′y32 = (p − p′) x32 + 2 (q − q′) x3y3 + m1,

(6)

m1 − 2T − pF2 − 2qFG − r1y32

(7)

so that

1( dx3) 2= X3
r2 dt

(8)