tan(A+B)/2=sinC
tan(180-C)/2=sinC
tan(90-(C/2))=sinC
cot(C/2)=sinC
cotc/2=cos(c/2)/sin(c/2)
sinc=2sin(c/2)cos(c/2)
所以有cos(c/2)/sin(c/2)=2sin(c/2)cos(c/2)
1＝2sin²(c/2)
sin²(c/2)=1/2
sin(c/2)=（根号2）/2
C/2=45
C=90
AB=1,那么AC=AB*cosA,BC=ABsinA
那么周长L=AB+AC+BC=1+sinA+cosA=1+根号2 sin(A+45)
由于0