答案1
有一条parabola
路径可供您使用。
\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[line width=.7pt]
\draw [->] (-.2,0)node[below]{$o$}--(4.5,0)node[below]{$x$};
\draw [->] (0,-.2)--(0,2)node[left]{$y$};
\draw (0,0) parabola[parabola height=1.2cm] (4,0);
\draw [->] (0,0)--(55:2);
\draw (0:.7cm)node[above left]{$\alpha$} arc (0:55:.7cm);
\end{tikzpicture}
\end{document}
答案2
开始使用 pgfplots :
\documentclass{article}
\usepackage{tikz}
\usepackage{pgfplots}
\pgfplotsset{compat=1.12}
\begin{document}
\begin{tikzpicture}
\begin{axis}[axis x line=bottom,
axis y line=left,]
\addplot[domain=0:5,
] {-(.5*x)*(x-5)};
\draw[->,] (axis cs:0,0) -- (axis cs:1,3);
\end{axis}
\end{tikzpicture}
\end{document}