prelude.sty

\usepackage{hyperref}
\hypersetup{
    pdftitle={Project Circinus v1.2.4},
    pdfsubject={Spherical trigonometry, and a whole load of baloney},
    pdfauthor={qihao}
}

\usepackage[utf8]{inputenc}
\usepackage[a4paper,margin=0.75in, footnotesep=0.25in]{geometry}
\usepackage[bottom]{footmisc}

\usepackage{xifthen}

\usepackage{parskip}
\usepackage{varwidth}
\usepackage{exercise}
\usepackage{enumitem}

\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{rotating}
\usepackage{graphicx}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}
\usepackage{tkz-euclide}
\usetikzlibrary{positioning,angles,calc,quotes,intersections,decorations.text,arrows,pgfplots.fillbetween}

\linespread{1.05}

%% 
%%  Exercise customization
%%
\renewcommand{\ExerciseHeader}{%
    \textbf{\ExerciseName\ \ExerciseHeaderNB\ ---}%
}%
\renewcommand{\AnswerHeader}{%
    \smallskip\textbf{Solution: }%
}%
\renewcommand{\ExerciseListHeader}{%
    \textbf{\ExerciseName\ \ExerciseHeaderNB\ --- }%
}%

%%
%%  Angle formatting commands
%%
\newcommand{\degree}{{}^{\circ}}
\newcommand{\sexg}[3]{%
    \ifthenelse{\isempty{#2}}%
        {{#1}\degree}%
        {\ifthenelse{\isempty{#3}}%
            {{#1}\degree {#2}'}%
            {{#1}\degree {#2}' {#3}''}%
        }%
}%
\newcommand{\hms}[3]{%
    \ifthenelse{\isempty{#2}}%
        {{#1}^{\mathrm{h}}}%
        {\ifthenelse{\isempty{#3}}%
            {{#1}^{\mathrm{h}} {#2}^{\mathrm{m}}}%
            {{#1}^{\mathrm{h}} {#2}^{\mathrm{m}} {#3}^{\mathrm{s}}}%
        }%
}%
\newcommand{\h}{{}^\mathrm{h}}
\newcommand{\RA}{\mathrm{RA}}
\newcommand{\HA}{\mathrm{HA}}
\newcommand{\EOT}{\mathrm{EOT}}

%%
%%  Layout commands
%%  
\newcommand{\flipanswer}[1]{\rotatebox[origin=c]{180}{\footnotesize #1}}

\setlength{\fboxsep}{0.75em}
\setlength{\fboxrule}{0.75pt}
\newcommand{\boxedtext}[1]{%
    \smallskip%
    \fbox{\begin{varwidth}{\textwidth}{#1}\end{varwidth}}%
    \smallskip%
}
\newcommand{\smallboxedtext}[1]{%
    \smallskip%
    \begin{center}\framebox{$\quad${#1}$\quad$}\end{center}%
    \smallskip%
}
\newcommand{\crule}{%
    \smallskip%
    \begin{center}\noindent\rule{0.5\textwidth}{0.4pt}\end{center}%
    \smallskip%
}

%%
%%  Counters
%%
\numberwithin{equation}{section}