\documentclass[12pt,letter]{article}
\newcommand{\PS}{Trig}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage[T1]{fontenc}
\usepackage[sc]{mathpazo}
\usepackage{fancyhdr}
\usepackage{boxedminipage}
\usepackage{polynom}
\usepackage{asymptote}
\usepackage{wrapfig}
%\usepackage{showkeys}
\newtheorem{theorem}{Theorem}
\newenvironment{proof}{\textbf{Proof:} }{}
\newtheorem{corollary}[theorem]{Corollary}
\newtheorem{lemma}[theorem]{Lemma}
\newtheorem{observation}[theorem]{Observation}
\newtheorem{proposition}[theorem]{Proposition}
\newtheorem{definition}[theorem]{Definition}
\newtheorem{claim}[theorem]{Claim}
\newtheorem{fact}[theorem]{Fact}
\newtheorem{assumption}[theorem]{Assumption}
\newcounter{exercise}[subsection]
\newcounter{problem}
\newcounter{solution}
\newcommand{\TODO}[1]{}
\newenvironment{exercise}{\par\vspace{.5in} \begin{boxedminipage}{.9\textwidth}\textbf{Exercise \arabic{section}.\arabic{subsection}.\arabic{exercise}:}\refstepcounter{exercise}\par}{\end{boxedminipage}\vspace{.5in}}
\renewcommand{\theexercise}{\arabic{section}.\arabic{subsection}.\arabic{exercise}}
\newenvironment{sproblem}{\textbf{Problem: }}{\par\vspace{.5in}}
\newenvironment{problem}{\textbf{Problem \arabic{problem}\addtocounter{problem}{1}: }}{\par\vspace{.5in}}
\newenvironment{solution}{\textbf{Solution to problem \arabic{solution}\addtocounter{solution}{1}: }}{\par}

\pagestyle{fancy}
\rhead{OCW Draft}
\begin{document}
\input{OCW\PS}
\end{document}