Question

Cos A.sin (B-C)+sin (C-A)+cos C.sin (A-B)=0

Answer 1

Step-by-step explanation:

cosA.sin(B-C)+cosB.sin(C-A)+cosC.sin(A-B)

=cosA(sinBcosC-cosBsinC)+ cosB.(sinCcosA-cosCsinA)+ cosC.(sinAcosB-cosAsinB)

=cosAsinBcosC-cosAcosBsinC+cosA cosBsinC-sinAcosBcosC+sinAcosBcosC-cosAsinBcosC

=0