(1452) 
- Therefore the direction cosines of the instantaneous 
axis are 
C — A À C — A 
nl — Sin y COS 
If « denotes the angle between the instantaneous axis 
[and C the geographical pole, these direction cosines 
are also — Sin « Sin #5, — Sin & COS vp, COS &. 
Hence 
tan = y ns tan &, 
p] 
so that 
C— A C—A 
ni, { —= —ntlanax cos 
p=ntanasin nt. 
Since y denotes the angle CZ and « the angle CI, and 
since C 1s greater than A, the instantaneous axis I lies 
on CZ produced beyond Z in the figure. 
We also have 
C 
tan IZ — 
