由正弦定理,容易得出:
(a^2-b^2)/c^2
=[(sinA)^2-(sinB)^2]/(sinC)^2
=(sinA+sinB)(sinB-sinB)/(sinC)^2
=4[sin(A+B)/2][cos(A-B)/2][sin(A-B)/2][cos(A+B)/2]/(sinC)^2
=sin(A+B)sin(A-B)/(sinC)^2
=sin(180°-C)sin(A-B)/(sinC)^2
=sin(A-B)/sinC.
由正弦定理,容易得出:
(a^2-b^2)/c^2
=[(sinA)^2-(sinB)^2]/(sinC)^2
=(sinA+sinB)(sinB-sinB)/(sinC)^2
=4[sin(A+B)/2][cos(A-B)/2][sin(A-B)/2][cos(A+B)/2]/(sinC)^2
=sin(A+B)sin(A-B)/(sinC)^2
=sin(180°-C)sin(A-B)/(sinC)^2
=sin(A-B)/sinC.