posted by C .
line segment ab is the diameter of circle O whose center has coordinates (6,8) . what are the coordinates of point b if the coordinates of point a are (4,2)
If centre has (6,8) and one end of the diameter has (4,2), add Δx and Δy to the centre to get the other end of the diameter, namely,
(Δx,Δy) = (6-4, 8-2) = (2,6)
So the other end of the diameter would be (6+2,8+6)=(8,14).
Check: the mid-point of the diameter should be the centre:
((4+8)/2,(2+14)/2)=(6,8) = centre of circle.