（2sinA+cosA)/(sinA-cosA)=-5
上下同除cosA
（2tanA+1)/(tanA-1)=-5
2tanA+1=-5tanA+5
7tanA=4
tanA=4/7
1.(sinA+cosA)/(sinA-cosA)
=(tanA+1)/(tanA-1)
=(4/7+1)/(4/7-1)
=-11/3
1+tan^2A=1/cosA^2
(cosA)^2=49/65
sinA^2=16/65
3cos2A+sin2A
=3(2cosA^2-1)+2sinAcosA
=99/65±2*28/65
=31/13或43/65