Determine Net Displacement Between GPS Locations

I'm trying to determine the net displacement between GPS locations and am wondering how I can easily code this in Excel. As far as I know, you need to calculate the distance between Point B to Point A, Point C to Point A, Point D to Point A, and so on. The following is the formula that I would use:

A
B
C

X_Coordinate
Y_Coordinate

123456
3700000
Point A

123460
3700010
Point B

Using the following formula (or setup), this is how I would calculate net displacement:

(123460-123456)^2+(3700010-3700000)^2 = (16)^2 + (10)^2 = 256 + 100 = 356

I assume if I want net squared displacement, I would square root this value SQRT(356) = 18.867

If my formula is correct above, I wonder why Excel gives me an answer for the following net displacement formula (same as above just using Excel formula): (A3-A2)^2 + (B3-B2)^2 = 116

Using this same formula, I could incorporate SQRT in as follows: =sqrt(((A3-A2)^2) + ((B3-B2)^2)), which results in 10.77. This value is clearly different than the value above (18.867) thus I wonder if I'm just mis-calculating something in Excel.