14/06/2026
\documentclass[tikz, border=5mm]{standalone}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}
\usetikzlibrary{arrows.meta, calc, shadings}
\usepackage{bm}
\newcommand{\rightAngle}[2]{
\begin{scope}[shift={ #1}, rotate= #2]
\draw[red, thin] (-0.4,0) -- (-0.4,-0.4) -- (0,-0.4);
\end{scope}
}
\begin{document}
%==============
% Example 13
%==============
\begin{tikzpicture}[scale=2.5]
\tikzset{
declare function={
xfun(\t)=-0.5*\t*\t-0.866*\t;
yfun(\t)=-0.866*\t*\t+0.5*\t;
}
}
\draw[magenta,very thick] plot[variable=\t,domain=-1.3:1.3,samples=200]
({xfun(\t)},{yfun(\t)});
\draw[very thick,dashed,->] (-2.1,0)--(2.1,0) node[right]{$\bm{x}$};
\draw[very thick,dashed,->] (0,-2)--(0,2) node[above]{$\bm{y}$};
\begin{scope}[rotate=-30]
\draw[magenta,->,very thick] (2,0)--(-2,0) node[above left,yshift=-0.5mm]{$\bm{y^{\prime}}$};
\draw[magenta,->,very thick] (0,-2)--(0,1.8) node[above right]{$\bm{x^{\prime}}$};
\node at (0,0) [magenta,below left]{$\bm{O^{\prime}}$};
\end{scope}
\draw[-stealth,line width=0.8pt](0:0.3) arc[start angle=0, end angle=60, radius=0.3]node[right,midway]{$\bm{60^{\circ}}$};
\draw[-stealth,line width=0.8pt](90:0.3) arc[start angle=90, end angle=150, radius=0.3]node[above,midway]{$\bm{60^{\circ}}$}; \node at (1.7,-1.6){$\bm{3x^2-2\sqrt{3}xy+y^2+2x+2\sqrt{3}y=0}$};
\node at (0.8,-2){$\bm{(y^{\prime})^2=-x^{\prime}}$};
\end{tikzpicture}
%===============
%Example 14
%===============
\begin{tikzpicture}[scale=0.7]
\draw[dashed,->,very thick] (-8,0)--(6,0) node[right]{$\bm{x}$};
\draw[dashed,->,very thick] (0,-5)--(0,7) node[above]{$\bm{y}$};
\begin{scope}[rotate=53.1]
\draw[magenta,->,very thick] (-4,0)--(6,0) node[above,xshift=2mm]{$\bm{x^{\prime}}$};
\draw[magenta,->,very thick] (0,-3)--(0,9) node[left,yshift=2mm]{$\bm{y^{\prime}}$};
\node at (0,0) [magenta,below left,xshift=-1mm]{$O^{\prime}$};
\end{scope}
\draw[magenta,very thick] plot[variable=\t,domain=-4.6:4.4,samples=200]
({((((\t*\t)/4-3)*0.6)-((\t+4)*0.8))},
{((((\t*\t)/4-3)*0.8)+((\t+4)*0.6))});
\draw[-stealth,very thick](0:1)arc[start angle=0, end angle=53.1, radius=1]node[right,midway]{$\bm{53.1^{\circ}}$};
\draw[magenta,dashed,very thick](-1.8,-2.4)--(-5,0);
\draw[magenta,dashed,very thick](-3.2,2.4)--(-5,0);
\rightAngle{(-1.8,-2.4)}{-126.9}
\rightAngle{(-3.2,2.4)}{53.1}
\filldraw[yellow](-3.2,2.4)circle(2pt)node[above right,magenta]{$\bm{4}$};
\draw[magenta,thick](-3.2,2.4)circle(3pt);
\filldraw[yellow](-5,0)circle(2pt);
\draw[magenta,thick](-5,0)circle(3pt);
\filldraw[yellow](-1.8,-2.4)circle(2pt)node[ right,black]{$\bm{-3}$};
\draw[magenta,thick](-1.8,-2.4)circle(3pt);
\node at (-6,7){$\bm{16x^2-24xy+9y^2+100x-200y+100=0}$};
\node at (-2.8,6){$\bm{(y^{\prime}-4)^2=4(x^{\prime}+3)}$};
\end{tikzpicture}
\end{document}