D would be the answer
From Q we know AB=OC=OB. Means triangle ABO and BCO are isoscles.
Means Angle BAD=Angle BDA = x
Means Angle DCB=Angle DBC = y
Stmt 1 - Angle COD = 60
=> Angle CDA = 120 = x + 180 - 2y => 2y-x = 60 -----(1)
Angle ABD = 180-y = 180-2x => 2x=y ------(2)
Solve 1 and 2 to get value x = 20 degree SUFF
Stmt 2 Angle BCD=40. Means Angle CBD=40
=> Angle ABD = 180-40 = 140
=> 2x+140 = 180.. Solve to get x = 20 SUFF
ANS D
GMAT Prep Geometry
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
