Question

Given M is the mid-point of AB, find the co-ordinates of B; if A = (3, –1) and M = (–1, 3).

Answer 1

Let B = (x, y), M = (–1, 3), A = (3, –1)

∴ `-1 = (x + 3)/2`

`=>` x + 3 = –2

∴ x = –2 – 3 = –5

`3 = (y - 1)/2`

`=>` y – 1 = 6

∴ y = 6 + 1 = 7

∴ Co-ordinates of B are (–5, 7)