Data Sufficiency

Hi,

I tried solving the sum by applying several triangle properties but could not get the [spoiler]OA = D[/spoiler]. Can someone pls mention the steps...




Thanks

Skywalker wrote:Hi,

I tried solving the sum by applying several triangle properties but could not get the [spoiler]OA = D[/spoiler]. Can someone pls mention the steps...




Thanks

https://www.beatthegmat.com/geometry-t67297.html#302732

I too tried this question, i think the correct answer will be C, by combining the A & B and using the property "exterior angle will be equal to sum of the two non-adjacent interior angles of a triangle"

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.

Hi GMATGuruNY,

COD is 60 but you took 30 and how did you calculated other angles.
Plz explain

deepak123gmat wrote:Hi GMATGuruNY,

COD is 60 but you took 30 and how did you calculated other angles.
Plz explain

In my post above there was a typo, which I just now corrected. Does this allay your confusion?