Fig. 3 PR 
== 2724 _— 4 Lz “ 
Pa EE sbbyy +307 Æ abxx | 
+Cbbzx — 46x + 36% R... — abby — 40% | 
+abxx — 2abbx — abby 
— ATV —2 abbzx 
x 40x a YIZ + 2a0ÿT — abT— 0 
4 | z 2 1 o 2 1 a 
Ge Æ Er ca x Fe 72 | D | 7 
Q + 120bx — 467 k +367 
ae + 2abx — 2abt AE — abb 
ga —12b2x— 2ayx + 2aby— 0 — AXD 
7 2 7 5 abyy—66ty — alt —0 | 
Pr = le F2 | Æ 
Æ e Z | 
mn 4 y } | / 
T.... +12 bb 1 
122% —24bx + 2ab— 0 
by 5bbyy + 2abxy + ab*= 0 
6by — 6tb — 0 
[o] 
