若\(O\)是\(\vartriangle ABC\)所在平面内一点，且满足\(\left| {{\rm{ }}\overrightarrow {OA} - \overrightarrow {OC} {\rm{ }}} \right| = \left| {{\rm{ }}\overrightarrow {OA} + \overrightarrow {OC} - 2\overrightarrow {OB} {\rm{ }}} \right|\)，则\(\vartriangle ABC\)的形状为___．
