@Mugwump303, what Lala means is this pic (below)

LalaB wrote:@Mugwump303
I didnt mean the triangle with E.(so, no need to find E)

my triangle is veerrry small and next to x angle.

revised
angle FGD is not necessarily 90`

stamped about angle E, changed previous solution

pemdas,

remember, if any of the sides of a triangle is a diameter of a circle, then that triangle is a right triangle
the big triangle must be a right triangle. then EGO is also a right triangle. FGD is one more right triangle. FGD is the triangle,which I meant in my 1st post

but do you follow the last post, of course two chords with diameter form a right triangle.
the point is that diameter must be parallel to the baseline of right triangle (big one) for other triangles to be right as well. Do you agree?

LalaB wrote:pemdas,

remember, if any of the sides of a triangle is a diameter of a circle, then that triangle is a right triangle
the big triangle must be a right triangle. then EGO is also a right triangle. FGD is one more right triangle. FGD is the triangle,which I meant in my 1st post

pemdas, when I solved it, I didnt need to find parallelism. I just proved that the bigger and smaller triangles are similar(not because of parallelism, but because they have the same angle, and the same 2 sides). so if ur big triangle is right, then EGO is also right
that is it

I am sorry, but you need to be vigilant when dealing with the similar triangles

I could show you dozens of not the similar triangles sharing the common angle and having the same direction sides (in different proportions). That's exactly what you are telling me now. The angle E is shared (common) and the two sides ..

LalaB wrote:pemdas, when I solved it, I didnt need to find parallelism. I just proved that the bigger and smaller triangles are similar(not because of parallelism, but because they have the same angle, and the same 2 sides). so if ur big triangle is right, then EGO is also right
that is it

pemdas, if I am not mistaken in ur previous post u assumed the same about right triangles. my q-do we have any chances to find a right answer without that assumptions? IMHO, it must be stated in a q., that figures are drawn to scale.otherwise, I can not see any chances to solve it
have ideas how to solve?

I cant watch that video. just curious what GMAT prep offer to do?

Okay, this must be a messed up problem or something. Because I think all the answer choices can work. The only way we would get just one correct answer choice is if we assume that the smaller triangle is a right triangle, but pemdas has shown that it doesn't have to be. I think this one is just a bad question.

we need GMATPREP instructor to explain this q.