[Tex/LaTex] How to label or dimension a circle radius in TikZ

tikz-pgf

I have a circle in the picture… How to add dimension of radius… form center of the circle to any point on the circle? Rotation is not giving what i want…

\documentclass[10pt]{article}
\usepackage{tikz}

\begin{document}

 \begin{tikzpicture}[scale=1.0]

\draw [step=1.0,thin,gray!40] (0,-3) grid (6,3);

\fill[blue] (3,0) circle (2pt) node [black,,below left] {$C$};
%
\draw[thick] (3,0) circle(3);

\draw[|->|] (3,0) -- (6,0)  node [midway,fill=white] {3$a$};
\draw[|->|,rotate=45] (3,0) -- (6,0)  node [midway,fill=white] {3$a$};

\end{tikzpicture}

\end{document}

Best Answer

Another option is to use relative polar coordinates for the 45° line as in (3,0) -- ++(45:3) and the option slope to let the node rotated in the direction of the line, i.e. node [midway,sloped,fill=white]

\documentclass[10pt]{article}
\usepackage{tikz}

\begin{document}

\begin{tikzpicture}[scale=1.0]

\draw [step=1.0,thin,gray!40] (0,-3) grid (6,3);

\fill[blue] (3,0) circle (2pt) node [black,below left] {$C$};
%
\draw[thick] (3,0) circle(3);
\begin{scope}[>=latex]
\draw[->] (3,0) -- (6,0)  node [midway,fill=white] {3$a$};
\draw[->] (3,0) -- ++(45:3)  node [midway,sloped,fill=white] {3$a$};
\end{scope}

\end{tikzpicture}

\end{document}

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[Tex/LaTex] How to put a coloured outline around fraction lines

Knuth in the TeXBook gave an example of "poor man's bold," (The TeXbook, p. 386) which can be typeset obtained by overprinting the normal weight symbol with slight offsets.

As he says:

The results are somewhat fuzzy, and they certainly are no match for the real thing if it's available; but poor man's bold is better than nothing, and once in a while you can get away with it.

Here, one can use a similar technique and the code is shown below:

\documentclass{article}
\usepackage{graphicx,xcolor} 
\usepackage{amsmath}
\def\PoorManContour#1#2#3{\leavevmode
    \setbox0=\hbox{{#1}}%
    \color{#3}\kern-.002em\copy0\kern-\wd0
    \color{#3}\raise-.04em\copy0\kern-\wd0
    \color{#3}\lower.04em\copy0\kern-\wd0
    \color{#3}\raise0.04em\copy0\kern-\wd0
    \color{#2}\raise-.012em\copy0\kern-\wd0
    \color{#2}\kern.06em\copy0\kern-\wd0
    \color{blue}\kern-.020em\lower.003em\box0
}
\begin{document}
\colorbox{gray!5}{\scalebox{5}{\PoorManContour{$\sqrt{\dfrac{A^3_i}{B^2}}$}{gray!60}{gray!60}}}
\end{document}

To achieve the best results possible one has to kern in small steps for possibly twenty steps or so. For simplicity, I have not done that. In the final version, you need to adjust the colors to suit, possibly changing the shading to white.

alt text

Edit

After reading Jan's comment below I read the manual and true, as the commenter said the easiest way to achieve what the OP wanted is to include the package without an option i.e., \usepackage{contour}. Helps to RFM!

[Tex/LaTex] Numerical conditional within tikz keys

I am definitely unfamiliar with both beamer and tikz (do not quite get what the \only are supposed to do) but perhaps this could go in the direction you want:

\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{chains}
\newcounter{count}

% helper macro:
\long\def\GobToSemiColon #1;{}

\newcommand\myPicture{
\begin{tikzpicture}
  \begin{scope}[start chain = going below]
  \ifnum\value{count}<1 \expandafter\GobToSemiColon\fi
  \ifnum\value{count}>3 \expandafter\GobToSemiColon\fi
  \node[draw, rectangle, on chain] {display only when counter is between
    1 and 3};

  \ifnum\value{count}>-1 \expandafter\GobToSemiColon\fi
  \node[draw, rectangle, on chain] {display only when counter is
    negative}; 

  \ifnum\value{count}<100 \expandafter\GobToSemiColon\fi
  \ifnum\value{count}>200 \expandafter\GobToSemiColon\fi  
  \node[draw, rectangle, on chain] {display only if counter is between
    100 and 200};

  \ifnum\value{count}<3 \expandafter\GobToSemiColon\fi
  \ifnum\value{count}>20 \expandafter\GobToSemiColon\fi
  \node[draw, circle, on chain] {only when counter is in the range 3 to 20};
  \end{scope}
\end{tikzpicture}
}

\begin{document}
\begin{frame}
\only{\setcounter{count}{-3}\myPicture}
\only{\setcounter{count}{105}\myPicture}
\only{\setcounter{count}{39}\myPicture}
\only{\setcounter{count}{2}\myPicture}
\only{\setcounter{count}{5}\myPicture}
\end{frame}
\end{document}

beamer

Best Answer

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[Tex/LaTex] Numerical conditional within tikz keys

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