The midpoint of AB is M (5,5). If the coordinates of A are (7,8) what are the coordinates of B?

Answer 1

Endpoint B (x,y) (missing therefore I called them x and y)

endpoint A (7,8)

midpoint M (5,5)

use your midpoint formula:

x₁+x₂ , y₁+y₂

¯¯2¯¯¯ ¯¯2¯¯

(x+7)/2 = 5 (mulitply the 2 on both side )

x+7 = 10 (subtract 7 on both side)

x = 3

(y+8)/2 = 5 (mulitply the 2 on both side )

y+8 = 10 (subtract 8 on both side)

y = 2

Endpoint B (3,2)