sin^2(A/2)=(c-b)/2c
2sin^2(A/2)=1-cosA
sin^2(A/2)=(1-cosA)/2=(c-b)/2c
即1-cosA=(c-b)/c
1 -cosA = 1 -b/c
即 cosA=b/c,则△ABC为直角三角形且∠C=90°
sin^2(A/2)=(c-b)/2c
2sin^2(A/2)=1-cosA
sin^2(A/2)=(1-cosA)/2=(c-b)/2c
即1-cosA=(c-b)/c
1 -cosA = 1 -b/c
即 cosA=b/c,则△ABC为直角三角形且∠C=90°