1.
在空间平移\(\triangle ABC\)到\(\triangle A_{1}B_{1}C_{1}(\)使\(\triangle A_{1}B_{1}C_{1}\)与\(\triangle ABC\)不共面\()\),连接对应顶点,设\(\overset{→}{A{A}_{1}}= \overset{→}{a} \),\(\overset{→}{AB}= \overset{→}{b} \),\(\overset{→}{AC}= \overset{→}{c} \),\(M\)是\(BC_{1}\)的中点,\(N\)是\(B_{1}C_{1}\)的中点,用基底\(\left\{ \overset{→}{a}, \overset{→}{b}, \overset{→}{c}\right\} \)表示向量\(\overrightarrow{AM}+\overrightarrow{AN}\)的结果是__________.