Hey !

I was going through the answers of assignment 8 while comparing to mine, and there is something I don't understand about the correction of the STEP question : after solving the equation system, we find that the two ellipses cross at the points (2;1) and (2;-1), then the correction sheet says "Any circle which passes through (2, 1) and (2, −1) must have its centre on the x axis, since
the x axis is the perpendicular bisector of the chord joining (2, 1) and (2, −1)". I may be wrong but shouldn't the "x-axis" be replaced by the "y-axis" in this sentence ?