girishbtg wrote: We have AB = OC = OB = r, the radius of circle in question. What is ∠BAO? ≡ ∠BAO = ∠BOA = let x =? ∴ ∠CBO = ∠BCO = 2 x. [1] If ∠COD = 60º, then ∠COA = 120º Or, ∠COB + ∠BOA = 120º Or, we have a linear in x, sufficient [2] If ∠BCO = 2 x = 40º, then x = 20º, sufficient [spoiler]D[/spoiler]

sanju09 wrote:girishbtg wrote: We have AB = OC = OB = r, the radius of circle in question. What is ∠BAO? ≡ ∠BAO = ∠BOA = let x =? ∴ ∠CBO = ∠BCO = 2 x. [1] If ∠COD = 60º, then ∠COA = 120º Or, ∠COB + ∠BOA = 120º Or, we have a linear in x, sufficient [2] If ∠BCO = 2 x = 40º, then x = 20º, sufficient [spoiler]D[/spoiler] Thanks for Responding... but still am not able to find out that how A ( i.e. eq 1 ) is sufficient in itself... Plz elaborate Thanks!

girishbtg wrote:sanju09 wrote:girishbtg wrote: We have AB = OC = OB = r, the radius of circle in question. What is ∠BAO? ≡ ∠BAO = ∠BOA = let x =? ∴ ∠CBO = ∠BCO = 2 x. [1] If ∠COD = 60º, then ∠COA = 120º Or, ∠COB + ∠BOA = 120º Or, ∠COB + ∠BOA = 120º Or, we have a linear in x, sufficient [2] If ∠BCO = 2 x = 40º, then x = 20º, sufficient [spoiler]D[/spoiler] Thanks for Responding... but still am not able to find out that how A ( i.e. eq 1 ) is sufficient in itself... Plz elaborate Thanks! [1] If ∠COD = 60º, then ∠COA = 120º Or, ∠COB + ∠BOA = 120º Or, 180º - 4 x + x = 120º Or, x = 20º. Hence, sufficient

sanju09 wrote:girishbtg wrote:sanju09 wrote:girishbtg wrote: We have AB = OC = OB = r, the radius of circle in question. What is ∠BAO? ≡ ∠BAO = ∠BOA = let x =? ∴ ∠CBO = ∠BCO = 2 x. [1] If ∠COD = 60º, then ∠COA = 120º Or, ∠COB + ∠BOA = 120º Or, ∠COB + ∠BOA = 120º Or, we have a linear in x, sufficient [2] If ∠BCO = 2 x = 40º, then x = 20º, sufficient [spoiler]D[/spoiler] Thanks for Responding... but still am not able to find out that how A ( i.e. eq 1 ) is sufficient in itself... Plz elaborate Thanks! [1] If ∠COD = 60º, then ∠COA = 120º Or, ∠COB + ∠BOA = 120º Or, 180º - 4 x + x = 120º Or, x = 20º. Hence, sufficient Great...! Thanks!

girishbtg wrote: When you want to see how the angles in a figure affect each other, plug in twice. The attached .pdf shows two sets of angle measurements that satisfy the requirements of the figure. In each case, we can see that COD:BAO = 3:1 and that BCO:BAO = 2:1. Statement 1: If COD = 60, then 60:BAO = 3:1, and BAO = 20. Sufficient. Statement 2: If BCO = 40, then 40:BAO = 2:1, and BAO = 20. Sufficient. The correct answer is D.