In the xy-coordinate plane, is point R equidistant from points (-3,-3) and (1,-3) ?
(1) The x-coordinate of point R is -1.
(2) Point R lies on the line y = -3.
Any point that lie on the perpendicular bisector the line segment with extreme points (-3,-3) and (1,-3) will satisfy this condition. The perpendicular bisector of the line segment is x=-1.
1) this means the point lies on x=-1. Sufficient.
2) This may or may not lie in the middle. The point -1,-3 is the mid point of the line segment but their are other points on the line such as (-2,-3) which doesn't satisfy the requirements. Insufficient.