[题目]设 |overrightarrow (a)|=3,, |overrightarrow (b)|=4,, |overrightarrow (c)|=5, 且满足-|||-overrightarrow (a)+overrightarrow (b)+overrightarrow (c)=0, 则 |overrightarrow (a)times overrightarrow (b)+overrightarrow (b)times overrightarrow (c)+overrightarrow (c)times overrightarrow (a)|= __ .