Question

证明题求解

(a^2-b^2)/c^2=[sin(A-B)]/sinC

Answer 1

(a^2-b^2)/c^2= （sin^2A-sin^2B）/sin^2C=( cos2B-cos2A) /2sin^2C=sin(A-B)sin(A+B)/sin^2C=[sin(A-B)]sinC/sin^2C==[sin(A-B)]/sinC