Final answer:
The abscissa (x1) is the horizontal coordinate of a point on the Cartesian plane, and the ordinate (y1) is the vertical coordinate. Without specific values, exact coordinates cannot be provided.
Step-by-step explanation:
The student is asking about a concept in mathematics related to the coordinate system, specifically within the context of graphing on the Cartesian plane. The abscissa, commonly referred to as x1, is the horizontal coordinate of the first point, which represents its distance from the y-axis. Similarly, the ordinate, or y1, is the vertical coordinate of the first point, indicating its distance from the x-axis. Without specific values provided for 'a', we cannot determine the exact values of x1 and y1. However, in general, if the point 'a' is represented as (x1, y1), then 'x1' is the abscissa and 'y1' is the ordinate.