Question

证明 |sinA-sinB|=

Answer 1

sinA=sin(A+B/2)cos(A-B/2)+sin(A-B/2)cos(A+B/2)

sinB=sin(A+B/2)cos(A-B/2)-sin(A-B/2)cos(A+B/2)

sinA-sinB=2sin(A-B/2)cos(A+B/2)

所以 |sinA-sinB|=| 2sin(A-B/2)cos(A+B/2)|=sinx