Question

The midpoint of AB is M(3,3). If the coordinates of A are (2, -1), what are the

coordinates of B?

Answer 1

(4, 7)

Explanation:

Given that:

Midpoint of AB = M(3, 3)

Coordinate of A = (2, - 1)

Let coordinates of B = (x, y)

Recall :

Midpoint of AB = [(Ax + Bx) / 2, (Ay + By) / 2]

Mx = (Ax + Bx) / 2

My = (Ay + By) / 2

Mx = 3

Mx = (Ax + Bx) / 2

3 = (2 + x) / 2

2*3 = 2 + x

6 = 2 + x

6 - 2 = x

4 = x

My = 3

My = (Ay + By) / 2

3 = (-1 + y) / 2

2*3 = - 1 + y

6 = - 1 + y

6 + 1 = y

7 = y

Hence,

B = (4, 7)