4 3 
Na = TF (115) 
XZ Gy Gq 
F F 
1 4 53 
= = => (116) 
Kvz 6, Gq 
F F 
1 4 3 
zd. td (117) 
Kvx E, Es 
G G 
4 3 
a TT TE (118) 
ZX E, Es 
E E 
4 3 
K! m mmm (119) 
XY F, F, 
e G G 
4 3 
K' = = - = (120) 
ZY Fy F4 
in which Eqs Fas and G4 refer to endpoint 3, and are computed according to equation (86); 
and E F, and G, refer to endpoint 4, and are similarly computed. 
In addition to the L -values defined by equations (98), (99) and (100), the 
following L'-values are introduced: 
is EAR T qe yn (121) 
uc rU e az 
de = + VEIIZ + (Ry)? (123) 
Applying the projective equations (87) to each of endpoints 1 and 3, and 
e subtracting, we obtain: 
X4 - Xi Es E, 
Yq - Y, = 9; F4 - 6, Fi (124) 
73 - Z4 Gy Gy 
i = - = -— m - 1 6 in: 
Letting AX 31 X3 Xi, AY 31 Yq Yi, and AZ31 Z4 Zi» and solving for 3° we obtain 
0. » ub KO + 2%) (125) 
3 E4 T 31 
or 
z 4 
63 = F, (F, 8, + AY 21) (126) 
or 
1 
= 12 
84 e (6,9, + AZ.) (127) 
- 23 +