What is the endpoint if a line segment with the endpoint (-1,9) and midpoint (-9,-10)

Answer 1

Let (x₁, y₁) represent the coordinates of the "other" endpoint, where the given endpoint is (-1,9). To find the coordinates of the midpt you take the average of the "x" coordinates and the average of the "y" coordinates.

Therefore:

x₁ + (-1)

----------- = -9 ; to solver for x₁ multiply both sides of the equation by 2, then add 1 to both sides.

2

y₁ + 9

--------- = -10 ; follow the same pattern.

2

Answer 2

The midpoint is half way.

(-1 + x)/2 = -9

-1 + x = -18

x = -17

(9 + y)/2 = -10

9 + y = -20

y = -29

(-17,-29)