\(\frac{5}{8}\)

\(\displaystyle\frac{5}{8}\)

\(\begin{align}
  & \frac{-b\pm \sqrt{{{b}^{2}}-4ac}}{2a} \\
& \triangle ABC\cong \triangle DEF \\
&  \\
& \angle ABC \\
&  \\
\end{align}\)

[ 本帖最後由 thepiano 於 2017-6-3 19:56 編輯 ]

\(\overset{\rightharpoonup }{\mathop{a}}\,\)
\(\overset{}{\mathop{a}}\,\)
\(\overset{}{\mathop{a}}\,\)
\(\overset{}{\mathop{AB}}\,\)
\(\overset{\underset{{}}{\longleftrightarrow}}{\mathop{AB}}\,\)
\(\overset{\overset{{}}{\longleftrightarrow}}{\mathop{AB}}\,\)