Drawing some simple pictures with tikz

Question

I've never drawn plots in Latex before and I'm really struggling at drawing some simple pictures with the tikz package. Can anybody help me? The two lines in the second and fourth quadrant should be made perpendicular to the vectors x_{.3} and x_{.1} respectively.

Answer 1

Perhaps this will get you started:

Here is the code:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning,arrows.meta}

\begin{document}

  \begin{tikzpicture}[>=Straight Barb]
    \draw[fill=black](105:1.6)--(285:0.6)-| cycle; % filled triangle
    \draw[orange](105:1.8)--(285:0.8);
    \draw[thick](0,2)node[above]{Security 2}--(0,0)--(2,0)node[right]{Security 1};
    \foreach \x [count=\xi] in {15,45,75} {
      \draw[->](0,0)--(\x:1.8);
      \node at (\x:2){$x_{\xi}$};
    }
  \end{tikzpicture}

\end{document}

Edit You can make the labels smaller by for example, ad \small to the labels. YOu can make the whole picture bigger by adding scale=3 to the tikzpicture environment -- there's alsoxscaleandyscale` if you want to scale by different factors in the x and y directions.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning,arrows.meta}

\begin{document}

  \begin{tikzpicture}[>=Straight Barb,scale=3]
    \draw[fill=black](105:1.6)--(285:0.6)-| cycle; % filled triangle
    \draw[orange](105:1.8)--(285:0.8);
    \draw[thick](0,2)node[above]{\small Security 2}--(0,0)--(2,0)node[right]{\small Security 1};
    \foreach \x [count=\xi] in {15,45,75} {
      \draw[->](0,0)--(\x:1.8);
      \node at (\x:2){$x_{\xi}$};
    }
  \end{tikzpicture}

\end{document}