\(\begin{array}{l}
\overrightarrow {AD} - \overrightarrow {FC} - \overrightarrow {EB} = \overrightarrow {CD} - \overrightarrow {EA} - \overrightarrow {FB} \\
\Leftrightarrow \overrightarrow {AD} + \overrightarrow {CF} + \overrightarrow {BE} + \overrightarrow {DC} + \overrightarrow {EA} + \overrightarrow {FB} = \overrightarrow 0 \\
\Leftrightarrow \left( {\overrightarrow {AD} + \overrightarrow {DC} } \right) + \left( {\overrightarrow {CF} + \overrightarrow {FB} } \right) + \left( {\overrightarrow {BE} + \overrightarrow {EA} } \right) = \overrightarrow 0 \\
\Leftrightarrow \overrightarrow {AC} + \overrightarrow {CB} + \overrightarrow {BA} = \overrightarrow 0 \\
\Leftrightarrow \overrightarrow {AB} + \overrightarrow {BA} = \overrightarrow 0 \left( {ld} \right)
\end{array}\)
