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DS-8
Source: Beat The GMAT — Data Sufficiency |
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simplyjat
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For these type questions, its better to draw the diagram on paper and assign the values.
From the question stem we know that AB = OB = OC. And the corresponding opposite angle should be similar
AB = OB -> BAO = BOA
OB = OC -> OBC = OBC
First information tells us COD = 60
let BAO = BOA = x
then BAO + BOC + COD = 180 (straight line)
=> x + BOC + 60 = 180. => BOC = 120-x
let OBC = OCB = y
also BOC + OCB + CBO = 180 (angles of triangle)
=> 120-x + y + y = 180 => 2y - x = 60 ..(I)
NOW OBC = BAO + BOA (exterior angle is sum of two other angles)
=> y = 2x ..(II)
solving I and II we get x = 20 thus first information is sufficient.
For the second information
we know that y = 40, and x = y/2 = 20....(x & y defined above) this this information is also sufficient.
From the question stem we know that AB = OB = OC. And the corresponding opposite angle should be similar
AB = OB -> BAO = BOA
OB = OC -> OBC = OBC
First information tells us COD = 60
let BAO = BOA = x
then BAO + BOC + COD = 180 (straight line)
=> x + BOC + 60 = 180. => BOC = 120-x
let OBC = OCB = y
also BOC + OCB + CBO = 180 (angles of triangle)
=> 120-x + y + y = 180 => 2y - x = 60 ..(I)
NOW OBC = BAO + BOA (exterior angle is sum of two other angles)
=> y = 2x ..(II)
solving I and II we get x = 20 thus first information is sufficient.
For the second information
we know that y = 40, and x = y/2 = 20....(x & y defined above) this this information is also sufficient.
simplyjat
