I took a practice test the other day and I came across a few DS questions that I was unable to figure out. If you know of a good way to break down these problems I would appreciate your help.
a) In the rectangular coordinate system, are the points (r,s) and (u,v) equidistant from the origin?
1) r + s = 1
2) u = 1 - r and v = 1 - s
1 clearly insufficient
2: distance (1-r)^2+(1-s)^2 = 1+r^2-2r+1+s^2-2s
we can't say it is equal to r^2+s^2
combining (1-r)^2+(1-s)^2 = r^2+s^2 so C.