LaTeX Forum

\newcommand[][0pt]{\maidt}{%
    \ensuremath{%
        \mathrel\phantom{=}%
        \hspace{#1}%
    }
}

\begin{align*}
  \begin{split}
    a &= b\\
    &\mathrel{\phantom{=}} foobar
  \end{split}
\end{align*}

\documentclass[10pt,a4paper]{scrartcl}
\usepackage[latin1]{inputenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\begin{document}
\begin{align} 
\sum{\overrightarrow{F_{ix}}} = 0 : \; \, 0&=A_H + F  \cos{\alpha}+C_H \\
\Rightarrow C_H&=-Fcos{\alpha}-A_H \\[\baselineskip]
%
\sum{{F_{iy}}} \uparrow ~ = 0 : \; \, 0&=A_V - F  \sin{\alpha}-C_V +
      \frac{F}{2} \\
\Rightarrow C_V&=A_V-F\sin{\alpha}+\frac{F}{2} \\[\baselineskip]
%
\begin{split}
   \sum{M_{iyC}} \curvearrowleft ~ = 0 : \; \, 
      0&=A_H r-A_V r + F\sin{\alpha}*r\cos{\alpha}\\ &\quad\,+F\cos{\alpha}(r-r\sin{\alpha})
\end{split}\\
\Rightarrow A_V&=A_H+F\sin{\alpha}\cos{\alpha}+
     F\cos{\alpha}(1-\sin{\alpha})
\end{align} 
\end{document}

\begin{eqnarray}
\owncount 
\displaystyle \sum{ \overrightarrow{F_{ix}}} = 0 : \; \, 0&=&A_H + F  \cos{\alpha}+C_H \\ \owncount
\Rightarrow C_H&=&-Fcos{\alpha}-A_H \\ \nonumber \\ \owncount
\displaystyle \sum{{F_{iy}}} \uparrow ~ = 0 : \; \, 0&=&A_V - F  \sin{\alpha}-C_V + \frac{F}{2} \\ \owncount
\Rightarrow C_V&=&A_V-Fsin{\alpha}+\frac{F}{2} \\ \nonumber \\ \owncount
\displaystyle \sum{M_{iyC}} \curvearrowleft ~ = 0 : \; \, 
0&=&A_H r-A_V r + F\sin{\alpha}*r\cos{\alpha}\\ \nonumber &+&F\cos{\alpha}(r-r\sin{\alpha}) \\ \owncount
\Rightarrow A_V&=&A_H+F\sin{\alpha}\cos{\alpha}+F\cos{\alpha}(1-\sin{\alpha}) \\ \nonumber 
\end{eqnarray}