Btukfyl

I am trying to draw the major sector below:

I have made some progress with the following code, but not quite what I want as I am having trouble filling the last bit of the sector.

documentclass{article}

usepackage[margin=0.5in]{geometry}

usepackage{pgfplots}

renewcommand{thesection}{arabic{section}}

usepackage{booktabs, makecell, multirow}

usepackage{stackengine,graphicx,xcolor}

usepackage{lscape}

usetikzlibrary{arrows}

usepackage{flexisym}

usetikzlibrary{shapes.geometric}

usetikzlibrary{decorations.markings}

newenvironment{tightcenter}{

setlengthtopsep{0pt}

setlengthparskip{0pt}

begin{center}}{end{center}}

begin{document}

begin{tikzpicture}[scale=1.2]

%cylinder

draw[black,thick,dotted] (0,0) circle (1.3cm);

fill[fill=black,opacity=0.8] (-0.2,0.2) circle (0.8mm);

%fill[fill=black,opacity=0.8] (+0.2,0.2) circle (0.8mm);

fill[fill=black,opacity=0.8] (-0.2,-0.2) circle (0.8mm);

fill[fill=black,opacity=0.8] (+0.2,-0.2) circle (0.8mm);

%draw [thick,dashed] (7,1) -- (8.2,1);

%draw[thick,<->](3.4,-1.52) to node[fill=white] {$3.5$ cm} (3.4,-3.22);

draw [thick,domain=95:355] plot ({1.3*cos(x)}, {1.3*sin(x)});

%

draw [thick,domain=94:270,fill=gray,opacity=0.5] plot ({1.3*cos(x)}, {1.3*sin(x)});

%draw [thick,domain=270:300,fill=red,opacity=0.5] plot ({1.3*cos(x)}, {1.3*sin(x)});

draw [thick] (1.3,-0.15) -- (0,0) -- (-0.15,1.3);

%\

draw [thick](0,0)++(0:0.25) arc (0:79:0.3);

node[above] at (0.4,0.2) {$50^{circ}$};

end{tikzpicture}

end{document}

You could draw your outline and fill it in one line of Code with draw [thick, fill=gray, fill opacity=0.5] (0,0) -- (95:1.3) arc (95:355:1.3) -- cycle;.

documentclass{article}

usepackage[margin=0.5in]{geometry}

usepackage{pgfplots}

renewcommand{thesection}{arabic{section}}

usepackage{booktabs, makecell, multirow}

usepackage{stackengine,graphicx,xcolor}

usepackage{lscape}

usetikzlibrary{arrows}

usepackage{flexisym}

usetikzlibrary{shapes.geometric}

usetikzlibrary{decorations.markings}

newenvironment{tightcenter}{

setlengthtopsep{0pt}

setlengthparskip{0pt}

begin{center}}{end{center}}

begin{document}

begin{tikzpicture}[scale=1.2]

%cylinder

draw[black,thick,dotted] (0,0) circle (1.3cm);



fill[fill=black,opacity=0.8] (-0.2,0.2) circle (0.8mm);

fill[fill=black,opacity=0.8] (-0.2,-0.2) circle (0.8mm);

fill[fill=black,opacity=0.8] (+0.2,-0.2) circle (0.8mm);



draw [thick, fill=gray, fill opacity=0.5] (0,0) -- (95:1.3) arc (95:355:1.3) -- cycle;



draw [thick](0,0)++(0:0.25) arc (0:79:0.3);

node[above] at (0.4,0.2) {$50^{circ}$};

end{tikzpicture}

end{document}

The (95:1.3) moves you to the starting point of your outer perimeter, after that you draw the arc arc (95:355:1.3) with the starting angle of 95, end angle of 355 and a radius of 1.3. Then you don't have to fiddle around with sine and cosine.

I hope I didn't misunderstood, what you wanted to achieve!

Best Regards!
Frieder

EDIT: I changed opacity=... to fill opacity=.... Otherwise, the dotted line would shine through.

And here is a picture: