In a last post I wanted to know the 3rd point of vertex, actually I have some similar problem ....
I think I have all data.. for example...:
3 vertex cordinates in order to have the direction(gray arrow):
v1 = (-0.117, 1.06,0.53) v2 = (0.82, 2.06, 0.76) v3 = (-0.63, 2.06, 0.76)distance between vertices:
d1 = 1.125 d2 = 1.43 d3 = 1.46distance between v3 and new vertice:
d4 = 0.8

actually I know that this problem have two possible solutions
also I tried with the last equation and with some 2d equation, also I search in all thread of math stackenchage without any good result.
thanks for any help.
Diego
thanks to @Moti for help
It is not clear what you are trying to solve. You use d3 twice. Do you tey to calculate a distance?
The following diagram might help you define better your need:
CE is perpendicular to CB and in the same plane.