(sinB+sinA)/sinC=(b+a)/c
因此sinBsinA=sin^2B-sin^2A
cos(A-B)+cos((180-(A+B))=1-(1-2sin^2C)
sinAsinB=sin^2C
联立等式
sin^2B-sin^2A=sin^2C
所以
b^2=a^2+c^2
所以是直角三角形
(sinB+sinA)/sinC=(b+a)/c
因此sinBsinA=sin^2B-sin^2A
cos(A-B)+cos((180-(A+B))=1-(1-2sin^2C)
sinAsinB=sin^2C
联立等式
sin^2B-sin^2A=sin^2C
所以
b^2=a^2+c^2
所以是直角三角形