Question

在△ABC中,已知sinA*sinB*cosC=sinA*sinC*cosB+sinB*sinC*cosA,若a,b,c

Answer 1

ab*(a^2+b^2-c^2)/2ab=ac*(a^2+c^2-b^2)/2ac+bc*(b^2+c^2-a^2)/2bc

a^2+b^2-c^2=a^2+c^2-b^2+b^2+c^2-a^2

a^2+b^2=2c^2

a*b)/(c^2)=