Fundamental concepts 29
c The trihedral case
;
,
;
(2.32)
(i = 1, 2, ···, 6).
d The line- symmetric octahedral case
;
(2.33)
.
e The plane- symmetric octahedral case
;
,
,
,
(2.34)
,
.
Figure 2.19 Chen and You’s double-Goldberg linkage.