Question

Help plz. M is the midpoint of AB. The coordinates of A are (-7,5) and the coordinates of Mare (- 9,0). Find the coordinates of

Answer 1

(-9, -2)

Explanation:

Given: A: (-7, 5)

M: (-9, 0)

Notice that the x-separation of A and M is 2;

That is, M is 2 units to the left of A.

Similarly, the y-separation is 5; M is 2 units below A.

Following this train of thought, we predict the coordinates of B as follows:

x-coordinate: subtract 2 from -7, obtaining -9;

y-coordinate: subtract 2 from 0, obtaining -2.

The coordinates of B are (-9, -2).

Answer 2

We can do a kind of point arithmetic,

M = (A + B)/2

2M = A + B

B = 2M - A

B = 2(-9,0) - (-7,5) = (-18 - -7, 0 -5) = (-11, -5)

Check:

(A+B)/2 = ( (-7,5)+(-11,-5) )/2 = (-18/2, 0/2) = (-9,0), good

Answer: B is (-11, -5)