I made a pair of sign errors at the end of the lecture
on Fri 2/11.  First, I wrote Tsin(theta) for the x-component 
of the tension, when it should have been -Tsin(theta).  Then 
I made a second sign error, using mg for W when I should have
used -mg, so that the two errors together gave the positive 
angle I was looking for.  Here is an explanation and the 
correct work.  This is also available as a pdf file and at
the Noble Library Copy Center.  I apologize for any confusion 
this might have caused.  GBA.