a^3+b^3-c^3=c^2(a+b-c)
a^3+b^3-c^3=ac^2+bc^2-c^3
a^3+b^3=c^2(a+b)
(a+b)(a^2-ab+b^2)=c^2(a+b)
a^2+b^2-ab=c^2
由余弦定理a^2+b^2-c^2=2abcosC得：
a^2+b^2=c^2+2abcosC
∵a^2+b^2=c^2+ab
∴cosC=1/2
∴C＝60°
∴A+B=120°
sinAsinB
=sinAsin[(2π/3)-A]
=sinA(sin2π/3cosA-cos2π/3sinA)
=(根號3/4)sin2A-1/4+(1/4)cos2A
=sin(2A-π/6)-1/4
=3/4
∴sin(2A-π/6)=1.
又∵-π/6