Vector AB with the end at point B (-5,12) has coordinates (-1,3) find the ordinate of point A.

Let the beginning of the vector AB, with the end at point B (-5; 12), have coordinates A (x; y). To determine the coordinates of the vector, it is necessary to subtract the corresponding coordinates of the beginning of the vector from the coordinates of the end of the vector, that is, the vector AB (-5 – x; 12 – y). On the other hand, the vector AB has coordinates (-1; 3). To find the coordinates of the beginning of the vector – point A, we equate these expressions: -5 – x = – 1; 12 – y = 3. Let’s solve the resulting equations: x = – 4; y = 8, then point A (- 4; 8). Answer. The ordinate of the point y = 8.