Gprep Question - Isosceles

[niraj_a]

Hi I need help with the attached question. If someone could explain the logic GMAC used to pick answer A I would appreciate it.

I understand the 2x+y=180 equation that can be used to solve this, where x are the two smaller equal angles, but how can we know that angle S is x for Statement 2?

Thank you!

[niraj_a]

anyone?

[jjw.ashish]

Statement 1 alone is sufficient because if one angle is 100 deg it cannot be forming the equal side because that would make the sum of two angles to 200 deg (more than the sum of angles of a triangle).

That leaves the two other angles to be isoceles. Sum = 80 (180 -100)
Hence individual angles is 40 deg

[niraj_a]

that makes perfect sense, i don't know why i didn't think of it on those lines, making me to pick D.

thank you so much!!

[sasi78]

I feel, good understanding of the properties of different types of triangles suchs as isoceles & equilateral is must to answer this kind of quesitons.