n(n≥3)个向量相加的法则适用于平面和空间直角坐标系
$$\eqalign{ & {a_1},{a_2},...,{a_n}\left( {n \geqslant 3} \right) \cr & {a_1} + {a_2} + ... + {a_n}, \cr & s = {a_1} + {a_2} + {a_3} + {a_4} + {a_5} \cr} $$
$$\eqalign{
& {a_1},{a_2},...,{a_n}\left( {n \geqslant 3} \right) \cr
& {a_1} + {a_2} + ... + {a_n}, \cr
& s = {a_1} + {a_2} + {a_3} + {a_4} + {a_5} \cr} $$