I have a simple tikzsketch that draws a vector relative to the center of a triangle and perpendicular to one of it's edges.
I would like to draw another path (vector) at the tip of the blue arrow in my sketch. I figure what I want to do is name the coordinate at the end of the path, but am not sure about the syntax of how to do that.
How do I capture / name a coordinate in a calculated path?
\documentclass[border=20pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{intersections, calc,through,backgrounds}
\begin{document}
\begin{tikzpicture}[scale=2]
% Coordinates for a triangle
\coordinate (P) at ($(0,0) + (rand,rand)$);
\coordinate (Q) at ($(2,-2) + .5*(rand, rand)$);
\coordinate (R) at ($(-2, -2) + .5*(rand, rand)$);
\coordinate (O) at (barycentric cs:P=1,Q=1,R=1) ;
%projection of O on PQ
%use this for the intersection point for the vector below
\coordinate (E) at ($(P)!(O)!(Q)$);
% Vector perpendicular to edge PQ and located at O
% I would like to get the coordinate at the tip of this vector
\draw[->, blue] let
\p1 = ($(P)-(Q)$)
in
(O)--node[midway, sloped, above]{$\vec{A}$}node[above,at end]{${\color{black}S}$}++($(O)!sqrt(\x1*\x1+\y1*\y1)!(E)-(O)$);
%\fill[red](S)circle(2pt)
\draw[thin] (P) -- (Q) -- (R) --cycle;
\end{tikzpicture}
\end{document}