# formulaI know that if I need to find the point that is exactly between 2 points I must average the points. How?

sciencesolve | Certified Educator

You need to remember the formula of a midpoint. Notice that this formula averages the coordinates of the points that stand at the left and the right of the midpoint such that:

`x = (x_A + x_B)/2`

and

hala718 | Certified Educator

For example, we have the points A(2,5) and the point B(4,3) and we need to find the point in between.

We will average both x and y coordinates to find the midpoint.

Let the midpoint be M(xM, yM).

==> xM = (xA+xB)/2 = (2+4)/2 = 6/2 = 3

==> yM = (yA+yB)/2 = (5+3)/2 = 8/2 = 4

Then, the midpoint is given by:

M (3,4)

giorgiana1976 | Student

To average 2 points, we'll have to calculate the arithmetical mean of the correspondent coordinates of the points.

If the point is located on a segment, at the same distance form both endpoints, this point is called endpoint.

Let's take 2 points M(x1,y1) and N(x2,y2).

The midpoint is P(x,y)

The distance PM = PN

PM^2 = (x1 - x)^2 + (y1 - y)^2

PN^2 = (x2 - x)^2 + (y2 - y)^2

(x1 - x)^2 + (y1 - y)^2 = (x2 - x)^2 + (y2 - y)^2

We'll expand the squares and we'll eliminate like terms:

x1^2 - x2^2 + y1^2 - y2^2 = 2xx1  - 2xx2 +  2yy1  - 2yy2

(x1 - x2)(x1 + x2) + (y1 - y2)(y1 + y2) = 2x(x1 - x2) + 2y(y1 - y2)

Comparing, we'll get:

2x(x1 - x2) = (x1 - x2)(x1 + x2)

We'll simplify and we'll get:

2x = (x1 + x2)

x = (x1 + x2)/2

y = (y1 + y2)/2

That's the proof of why you has to average the points!