证明:右边= [(sin(A-B)]/sinC
=(sinAcosB-cosAsinB)/sinC
=(acosB-bcosA)/c
=[(a²+c²-b²)/(2c)- (b²+c²-a²)/(2c)]/c
=(a²-b²)/c²
=左边,
∴等式得证.
证明:右边= [(sin(A-B)]/sinC
=(sinAcosB-cosAsinB)/sinC
=(acosB-bcosA)/c
=[(a²+c²-b²)/(2c)- (b²+c²-a²)/(2c)]/c
=(a²-b²)/c²
=左边,
∴等式得证.