When you want to see how the angles in a figure affect each other, plug in twice. Plugging in for the angle measurements makes it much easier to see what's going on. Just be sure to follow the rules of geometry as you plug in:
Angles inside a triangle must add up to 180.
Angles opposite equal sides of a triangle must be equal.
Angles that form a straight line must add up to 180.
etc.
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.
Now it's easy to see what we need to answer the question: to determine the value of BAO, we need to know either COD or BCO.
Statement 1:
Tells us COD = 60. Sufficient. (If COD = 60, then plugging into COD:BAO = 3:1 we get 60:BAO = 3:1, and BAO = 20.)
Statement 2:
Tells us BCO = 40. Sufficient. (If BCO = 40, then plugging into BCO:BAO = 2:1 we get 40:BAO = 2:1, and BAO = 20.)
The correct answer is D.
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Attachments
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- Angle_relationships_GMATPrep.pdf
- (36.41 KiB) Downloaded 186 times
Last edited by
GMATGuruNY on Thu Oct 07, 2010 6:48 am, edited 1 time in total.
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