AB
Write the coordinates in the boxes.  Then press 

xA = yA =
xB = yB =

d(A,B) =    slope =

direction = °

xM =    yM =

line AB:  (y-yA)*(xA-xB) = (x-xA)*(yA-yB)  or:  (xA-xB)*y+(yB-yA)*x = xA*yB-yA*xB
or:  x = xA+(xB-xA)*t, y = yA+(yB-yA)*t    or:   y = slope*(x-xA)+yA
perpendicular bisector:  y = -1/slope*(x-xM)+yM
direction vector: x = (xB-xA)/d(A,B), y = (yB-yA)/d(A,B)

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calculator

 
=   A
(you can use "A" as one or both inputs)

If you have to put a coefficient using some function symbol (for example 1/5, √2), put it in a numerical form (0.2, 1.414213562373095), for example using this (or this)

examples