B -1-2,2第一题用三角代换第二题把c2替换掉,简单变换得出答案.先由(a2-c2)(a2-d2)=1,(b2-c2)(b2-d2)=1,把c2消掉,得出a,b,d的关系,然后(a2-c2)(a2-d2)=1得出c2=a2-1/(a2-d2)代入a2b2-c2d2,化简,综合前面得出a,b,d的关...