Question

The midpoint of AB is M(- 2, 1) . If the coordinates of (1, - 2) , what the coordinates of B?

Answer 1

(-5, 4)

Explanation:

Finding the X of B

-2 = x2+x1/2

-2 = x2+1/2 (substituted X co-ord of A into x1)

-4=x2+1 (multiplied both sides by 2)

-5=x2 (brought 1 to the other side)

Finding the Y of B

1 = y2+y1/2

1 = y2 - 2/2 (substituted Y co-ord of A into y1)

2 = y2 -2 (multiplied both sides by 2)

4 = y2 (brought 2 to the other side)