How to add perpendicular symbol at desired location

Question

I am trying to draw perpendicular symbol on point where the perpendicular line from O is meeting the line AB. But I am unable to achieve it. I try via simple draw because I use pgfplots (you can see in MWE, I had tried tkz-euclide but in vain). Kindly help.

MWE:

\documentclass{article}

\usepackage{graphicx}
\usepackage{amsmath}

\usepackage{tkz-euclide} % loads  TikZ and tkz-base
\usetkzobj{angles} % important you want to use angles

\usepackage{pgfplots}
\usetikzlibrary{angles,quotes,calc}
\pgfplotsset{compat=1.15}

\begin{document}

\begin{tikzpicture}[scale=1.5]
\begin{axis}[
        % legend pos=outer north east,
        xmin=0, xmax=3,    ymin=0,    ymax=3,
        xlabel = {X}, ylabel = {Y}, 
        ytick=\empty,
        xtick=\empty,
        clip=false, 
        grid = major, axis lines = middle  ,
        axis line style={gray}
        ]

    \def\uu{\large $\hat{u}$};
    \def\vu{\large $\hat{v}$};
    \def\au{\large $\vec{a}$};
    \def\bu{\large $\vec{b}$};
    \def\cu{\large $\vec{c}$};
    \coordinate (o) at (0,0);
    \coordinate (a) at (1, 2);

    \coordinate (b) at (2, 0.5);


    \coordinate (u) at (0.26, 0.52);
    \coordinate (v) at (0.52, 0.13);

    \coordinate (i) at (0.5,0);
    \coordinate (j) at (0,0.5); 

    % \draw pic[draw,fill=cyan!30,angle radius=1.6cm,"$\beta$" shift={(9mm,2mm)}] {angle=i--o--u};
    % \draw pic[draw,fill=red!30,angle radius=1.2cm,"$\alpha$" shift={(6mm,2mm)}] {angle=i--o--v};
    \draw pic[draw,fill=green!30,angle radius=1cm,"$\theta$" shift={(1mm,1mm)}] {angle=b--o--a};


    \draw[line width=2pt,blue,-stealth](o)--(a) node[anchor=south west, xshift=-2mm, yshift=-1mm]{A}; % vector a
    \draw[line width=2pt,red,-stealth](o)--(b) node[anchor=south west, xshift=-1mm, yshift=-2mm]{B};   % vector b
    \draw[line width=2pt,green!60!black,-stealth](a)--(b);   % vector c

    \draw[line width=2pt,blue,-stealth](o)--(u) node[anchor=south east, yshift=-2mm]{\uu};
    \draw[line width=2pt,red,-stealth](o)--(v) node[anchor=south west, xshift=-2mm]{\vu};

    \draw[line width=1.5pt,-stealth](o)--(i) node[below=6mm, anchor=south east]{$\hat{i}$};
    \draw[line width=1.5pt,-stealth](o)--(j) node[anchor=south east]{$\hat{j}$};

    % perpendicular line
    % https://tex.stackexchange.com/questions/19348/how-to-draw-a-line-passing-through-a-point-and-perpendicular-to-another
    \draw ($(a)!(o)!(b)$) -- (o);

    \node [above] at (0.51, 1.28) {$\vec{a}$};
    \node [below] at (1.42, 0.35) {$\vec{b}$};

    % BELOW LINES DO NOT ADD SYMBOL AT RIGHT PLACE. 
    \coordinate (X) at (o |- a);
    \draw ($(X)!5pt!(o)$) -| ($(X)!5pt!(a)$);  

  \end{axis}

  % BELOW IS DRAWING AT WRONG PLACE
    % \tkzDefPoint(0,0){O}
    % \tkzDefPoint(1,2){A}
    % \tkzDefPoint(2,0.5){B}
    % \tkzDefPointBy[projection=onto B--A](O)  \tkzGetPoint{H};
    % \tkzMarkRightAngle[fill=blue!20,size=.5](O,H,B);

\end{tikzpicture}



\end{document}

Output:

score 3 · Accepted Answer · 2018-11-08T14:50:45.387

Something like this?

\documentclass{article}

\usepackage{amsmath}

\usepackage{pgfplots}
\usetikzlibrary{angles,quotes,calc}
\pgfplotsset{compat=1.15}

\begin{document}
\begin{tikzpicture}[scale=1.5]
\begin{axis}[
        % legend pos=outer north east,
        xmin=0, xmax=3,    ymin=0,    ymax=3,
        xlabel = {X}, ylabel = {Y}, 
        ytick=\empty,
        xtick=\empty,
        clip=false, 
        grid = major, axis lines = middle  ,
        axis line style={gray}
        ]

    \def\uu{\large $\hat{u}$};
    \def\vu{\large $\hat{v}$};
    \def\au{\large $\vec{a}$};
    \def\bu{\large $\vec{b}$};
    \def\cu{\large $\vec{c}$};
    \coordinate (o) at (0,0);
    \coordinate (a) at (1, 2);

    \coordinate (b) at (2, 0.5);


    \coordinate (u) at (0.26, 0.52);
    \coordinate (v) at (0.52, 0.13);

    \coordinate (i) at (0.5,0);
    \coordinate (j) at (0,0.5); 

    % \draw pic[draw,fill=cyan!30,angle radius=1.6cm,"$\beta$" shift={(9mm,2mm)}] {angle=i--o--u};
    % \draw pic[draw,fill=red!30,angle radius=1.2cm,"$\alpha$" shift={(6mm,2mm)}] {angle=i--o--v};
    \draw pic[draw,fill=green!30,angle radius=1cm,"$\theta$" shift={(1mm,1mm)}] {angle=b--o--a};


    \draw[line width=2pt,blue,-stealth](o)--(a) node[anchor=south west, xshift=-2mm, yshift=-1mm]{A}; % vector a
    \draw[line width=2pt,red,-stealth](o)--(b) node[anchor=south west, xshift=-1mm, yshift=-2mm]{B};   % vector b
    \draw[line width=2pt,green!60!black,-stealth](a)--(b);   % vector c

    \draw[line width=2pt,blue,-stealth](o)--(u) node[anchor=south east, yshift=-2mm]{\uu};
    \draw[line width=2pt,red,-stealth](o)--(v) node[anchor=south west, xshift=-2mm]{\vu};

    \draw[line width=1.5pt,-stealth](o)--(i) node[below=6mm, anchor=south east]{$\hat{i}$};
    \draw[line width=1.5pt,-stealth](o)--(j) node[anchor=south east]{$\hat{j}$};

    % perpendicular line
    % https://tex.stackexchange.com/questions/19348/how-to-draw-a-line-passing-through-a-point-and-perpendicular-to-another
    \draw ($(a)!(o)!(b)$) coordinate(aux0)  -- (o);
    \draw ($(aux0)!2mm!(b)$) -- ++ ($($(aux0)!2mm!(o)$)-(aux0)$) -- ($(aux0)!2mm!(o)$);

    \node [above] at (0.51, 1.28) {$\vec{a}$};
    \node [below] at (1.42, 0.35) {$\vec{b}$};

    % BELOW LINES DO NOT ADD SYMBOL AT RIGHT PLACE. 
  \end{axis}

\end{tikzpicture}
\end{document}

no marmot, I need the perpendicular sign, something like discussed here — Parthiban Rajendran, Nov 08 '18 at 14:39

score 1 · Answer 2 · answered Nov 08 '18 at 14:51

There might be an easier way, but I can't read french.

\documentclass{article}

\usepackage{graphicx}
\usepackage{amsmath}

\usepackage{tkz-euclide} % loads  TikZ and tkz-base
\usetkzobj{angles} % important you want to use angles

\usepackage{pgfplots}
\usetikzlibrary{angles,quotes,calc}
\pgfplotsset{compat=1.15}

\begin{document}

\begin{tikzpicture}[scale=1.5]
\begin{axis}[
        % legend pos=outer north east,
        xmin=0, xmax=3,    ymin=0,    ymax=3,
        xlabel = {X}, ylabel = {Y}, 
        ytick=\empty,
        xtick=\empty,
        clip=false, 
        grid = major, axis lines = middle  ,
        axis line style={gray}
        ]

    \def\uu{\large $\hat{u}$};
    \def\vu{\large $\hat{v}$};
    \def\au{\large $\vec{a}$};
    \def\bu{\large $\vec{b}$};
    \def\cu{\large $\vec{c}$};
    \coordinate (o) at (0,0);
    \coordinate (a) at (1, 2);

    \coordinate (b) at (2, 0.5);


    \coordinate (u) at (0.26, 0.52);
    \coordinate (v) at (0.52, 0.13);

    \coordinate (i) at (0.5,0);
    \coordinate (j) at (0,0.5); 

    % \draw pic[draw,fill=cyan!30,angle radius=1.6cm,"$\beta$" shift={(9mm,2mm)}] {angle=i--o--u};
    % \draw pic[draw,fill=red!30,angle radius=1.2cm,"$\alpha$" shift={(6mm,2mm)}] {angle=i--o--v};
    \draw pic[draw,fill=green!30,angle radius=1cm,"$\theta$" shift={(1mm,1mm)}] {angle=b--o--a};


    \draw[line width=2pt,blue,-stealth](o)--(a) node[anchor=south west, xshift=-2mm, yshift=-1mm]{A}; % vector a
    \draw[line width=2pt,red,-stealth](o)--(b) node[anchor=south west, xshift=-1mm, yshift=-2mm]{B};   % vector b
    \draw[line width=2pt,green!60!black,-stealth](a)--(b);   % vector c

    \draw[line width=2pt,blue,-stealth](o)--(u) node[anchor=south east, yshift=-2mm]{\uu};
    \draw[line width=2pt,red,-stealth](o)--(v) node[anchor=south west, xshift=-2mm]{\vu};

    \draw[line width=1.5pt,-stealth](o)--(i) node[below=6mm, anchor=south east]{$\hat{i}$};
    \draw[line width=1.5pt,-stealth](o)--(j) node[anchor=south east]{$\hat{j}$};

    % perpendicular line
    % https://tex.stackexchange.com/questions/19348/how-to-draw-a-line-passing-through-a-point-and-perpendicular-to-another
    \coordinate (X) at ($(a)!(o)!(b)$);
    \draw (X) -- (o);

    \node [above] at (0.51, 1.28) {$\vec{a}$};
    \node [below] at (1.42, 0.35) {$\vec{b}$};

    % ADD PERPENDICULAR SYMBOL
    \coordinate (Xo) at ($(X)!5pt!(o)$);
    \coordinate (Xb) at ($(X)!5pt!(b)$);
    \draw (Xo) -- ($(Xo)!5pt!-45:(Xb)$) -- (Xb);

  \end{axis}

  % BELOW IS DRAWING AT WRONG PLACE
    % \tkzDefPoint(0,0){O}
    % \tkzDefPoint(1,2){A}
    % \tkzDefPoint(2,0.5){B}
    % \tkzDefPointBy[projection=onto B--A](O)  \tkzGetPoint{H};
    % \tkzMarkRightAngle[fill=blue!20,size=.5](O,H,B);

\end{tikzpicture}

\end{document}

How to add perpendicular symbol at desired location

2 Answers2

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