Thank you very much, it worked but i adjust code a bit.
SpawnPosition = [aPos,bPos,cPos] call BIS_fnc_selectRandom;
InfGroup = [getPos SpawnPosition, Resistance, ["TK_GUE_Soldier_2_EP1", "TK_GUE_Soldier_EP1",
"TK_GUE_Soldier_AT_EP1", "TK_GUE_Soldier_EP1", "TK_GUE_Soldier_EP1", "TK_GUE_Soldier_EP1",
"TK_GUE_Soldier_EP1", "TK_GUE_Soldier_TL_EP1", "TK_GUE_Soldier_AR_EP1"], [], [], [], [], [], 210] call BIS_fnc_spawnGroup;
[infGroup, getPos Target] call BIS_fnc_taskAttack;