In the figure shown, point O is the center of :: Manhattan GMAT Forums

Posted: Sat Aug 11, 2007 2:21 pm

OC is the radius here, so if AB = OC then AB = OB.

1) If COD = 60'

Suppose BOA = x, then BAO = x from isoceles, then CBO = 2x (external angle of a triangle), BCO = 2x (again isoceles BOC),

Now , COD = 60 = 180 - COA = 180 - COB - BOA = 180 - (180 - (COB + CBO)) - x = 180 - (180-4x) - x = 3x

3x = 60, x = 20' = BAO.

2) BCO = 40, so CBO = 40 (Isoceles BOC), since CBO is external angle of triangle ABO, BAO + BOA = 40, BAO = BOA (Isoceles) so each of them is 20'. So BAO = 20'.

Each statement alone is sufficient.

Posted: Sat Aug 11, 2007 6:49 pm

Great! That is the answer. During my practice test, I could figure out a way only using the Statement(2).