alignat 环境中的列表被推到右侧

Question

如何让此列表水平居中？

\documentclass{amsart}
\usepackage{amsmath}
\usepackage{amsfonts}


\begin{document}


\noindent {\bf Example} \vskip1.25mm
\noindent \hspace*{1em}
\begin{minipage}{5.75in}
Verify the following evaluations of the sine and cosine functions. 
\begin{alignat*}{6}
{\mathrm{i.})} \ &\sin(120^{\circ}) = \frac{\sqrt{3}}{2}
\qquad \quad
&{\mathrm{ii.})} \ &\sin(135^{\circ}) = \frac{\sqrt{2}}{2}
\qquad \quad
&{\mathrm{iii.})} \ &\sin(150^{\circ}) =  \frac{1}{2} \\
{\mathrm{iv.})} \ &\cos(120^{\circ}) = -\frac{1}{2}
\qquad \quad
&{\mathrm{v.})} \ &\cos(135^{\circ}) = -\frac{\sqrt{2}}{2}
\qquad \quad
&{\mathrm{vi.})} \ &\cos(150^{\circ}) = -\frac{\sqrt{3}}{2}
\end{alignat*}
\end{minipage}

\end{document}

Answer 1

删除使用minipage, as align- 及其朋友相对于文本块的中心：

\documentclass{amsart}
\usepackage{showframe}% Just for this example

\begin{document}

\noindent \textbf{Example}

\noindent
Verify the following evaluations of the sine and cosine functions. 
\begin{alignat*}{6}
  \textrm{i.)~}     & \sin(120^{\circ}) = \frac{\sqrt{3}}{2} \qquad \quad
  & \textrm{ii.)~}  & \sin(135^{\circ}) = \frac{\sqrt{2}}{2} \qquad \quad
  & \textrm{iii.)~} & \sin(150^{\circ}) = \frac{1}{2} \\
  \textrm{iv.)~}    & \cos(120^{\circ}) = -\frac{1}{2} \qquad \quad
  & \textrm{v.)~}   & \cos(135^{\circ}) = -\frac{\sqrt{2}}{2} \qquad \quad
  & \textrm{vi.)~}  & \cos(150^{\circ}) = -\frac{\sqrt{3}}{2}
\end{alignat*}

\end{document}

Answer 2

并不是真正居中，但编号是随着任务自动进行的package，并且代码也更简单：

\documentclass{amsart}
\usepackage[showframe]{geometry} 
\usepackage{tasks}
\settasks{counter-format=(tsk[a]), label-offset = 0.5em, label-align=right, column-sep=3em, before-skip=1.5ex}

\begin{document}

\noindent \textbf{Example}\bigskip

\noindent
Verify the following evaluations of the sine and cosine functions.
     \begin{tasks}[counter-format=tsk[r].),label-width=2em](3)
            \task $\sin(120^{\circ}) = \frac{\sqrt{3}}{2}$
            \task $ \sin(135^{\circ}) = \frac{\sqrt{2}}{2}$
            \task $ \sin(150^{\circ}) = \frac{1}{2}$
            \task $ \cos(120^{\circ}) = -\frac{1}{2}$
            \task $\cos(135^{\circ}) = -\frac{\sqrt{2}}{2}$
            \task $ \cos(150^{\circ}) = -\frac{\sqrt{3}}{2} $
            \end{tasks}

\end{document}