The coordinates of point T are (-4, 0). The midpoint of ST¯¯¯¯¯¯¯ is (-5, 7). Find the coordinates of S.

Answer 1

The midpoint is obtained from two points S (x,y) and T(x₁, y₁); midpoint =( (x + x₁)/2 , (y + y₁)/2)

so for the x coordinate for S:

1. -5 = (x + (-4))/2 do normal algebra, mult. both sides by 2, then add 4 to find the x value at point T.
2. -10 + 4 = x; x = -6
3. repeat for the y value at point T
4. 7 = (y +0)/2
5. 14 = y
6. (x,y) coordinate for point T: (-6,14)

Hopefully, you understood how to use the formula for midpoint (of two points) and use that formula to find one of the end points (for T).