Mdthbs

I'm working in a project for university using latex and i'll make a gif explaning the radians of math! And I really dont know how to make this type of line (i'll put the example below) !! Plz help me guys!!

The project that ive done so far :D
http://www.mediafire.com/file/wc4xazt8k4h4t5h/testeAnime.pdf/file

WHAT IVE DONE :D

documentclass[border=1cm]{standalone}

usepackage[utf8]{inputenc}

usepackage{tikz}

begin{document}



begin{tikzpicture}











begin{scope}

draw (0,0) circle (10cm);

draw[line width=0.15cm, blue] (10,0) arc (0:360:10) ;



draw[-] (-12,0) -- (12,0) node[right] {$x$};

draw[-] (0,-12) -- (0,12) node[above] {$y$};

draw[line width=0.15cm,red] (0,0) -- (10,-0);

node[scale=15.5, red, right, opacity=0.5] at (2,2) {r};



draw[red][fill] (0,0) circle (0.2cm);

draw[red][fill] (10,-0) circle (0.2cm);





  end{scope}





end{tikzpicture}



end{document}

A PSTricks solution only for fun purposes.

documentclass[pstricks,border=12pt,12pt]{standalone}

radians

defobj#1{%

begin{pspicture}(-4,-4)(4,4)

    pscircle{4}

    psset{linecolor=red,linewidth=2pslinewidth}

    psarc(0,0){4}{0}{#1}

    rput{#1}(4;#1){psline(!0 1 #1 sub 4 mul)}

end{pspicture}}

begin{document}

    foreach i in {0,0.1,...,1.0}{obj{i}}

end{document}

If you wish to produce such animated gifs, you may want to compile

documentclass[border=1cm,tikz]{standalone}

usetikzlibrary{arrows.meta}

begin{document}

foreach X in {180,175,...,90}

{begin{tikzpicture}

begin{scope}

draw (0,0) circle (10cm);

draw[line width=0.15cm, blue] (10,0) arc (0:360:10) ;

draw[-] (-12,0) -- (12,0) node[right] {$x$};

draw[-] (0,-12) -- (0,12) node[above] {$y$};

draw[line width=0.15cm,red,{Circle}-{Circle},shorten >=-2*pgflinewidth,shorten

<=-2*pgflinewidth] (10,0) -- ++(X:10);

node[scale=15.5, red, right, opacity=0.5] at (2,2) {r};

end{scope}

end{tikzpicture}}

end{document}

with pdflatex and then convert the resulting pdf with

convert -density 300 -delay 34 -loop 0 -alpha remove outfile.pdf ani.gif

to get

Or

documentclass[border=1cm,tikz]{standalone}

usetikzlibrary{arrows.meta}

begin{document}

foreach X in {0,5,...,90}

{begin{tikzpicture}

draw[line width=0.15cm, blue] circle[radius=10cm];

draw[-] (-12,0) -- (12,0) node[right] {$x$};

draw[-] (0,-12) -- (0,12) node[above] {$y$};

draw[line width=0.15cm,red,{Circle}-{Circle},shorten >=-2*pgflinewidth,shorten

<=-2*pgflinewidth] (0,0) -- ++(-X:10)

node[scale=15.5, red, midway,above,sloped,opacity=0.5] at (2,2) {r};

end{tikzpicture}}

end{document}

Or, inspired by this answer

documentclass[border=1cm,tikz]{standalone}

usetikzlibrary{arrows.meta}

begin{document}

foreach X in {0,5,...,90}

{begin{tikzpicture}

draw[line width=0.15cm, blue] circle[radius=10cm];

draw[-] (-12,0) -- (12,0) node[right] {$x$};

draw[-] (0,-12) -- (0,12) node[above] {$y$};

draw[line width=0.15cm,red,{Circle}-{Circle},shorten >=-2*pgflinewidth,shorten

<=-2*pgflinewidth] (10,0) arc(0:{2*X/pi}:10) -- ++ ({2*X/pi+90}:{10-10*X/90});

end{tikzpicture}}

end{document}