17.(本题共12分)【解】(1)(方法一)'acos C+ccos A=2,+6-e*2-d-2,a·+C2ab2bc.2b2=4b.b≠0,.b=2.(2分)am8c1g14r-么,2ac(4分)cos 4=+c2-a214cA(0,T3案解析网(6分)(方法=)asG+A2,a,eed=2,+c2ab2be.262=46.b≠0,,b=2.(2分)cc in co Bsin Cin B2血4sBm:8)兮n8=血Am8a4n8rn8、1