amirhakimi wrote:Aren't P and Q symmetry upon y-axis?
Nope they are not symmetric. We should not rely on the GMAT to provide us figures drawn to scale (implying you cannot use a protractor to measure their diagrams

)
In the figure shown, points P and Q lie on the circle with center O. What is the value of s?
(A) 1/2
(B) 1
(C) √2
(D) √3
(E) 1/√2
Consider the above problem again:
In ∆PAO, the sides are 1, √3, and 2. Thus it is a 30-60-90 triangle as shown.
Complete the other angles and drop a perpendicular to B. It is our new 30-60-90 triangle.
The sides are again 1, √3, and 2.
thus Q has the co-ordinates (s,t) = [spoiler](1, √3) and s = 1[/spoiler]