Verify that sin(A+B)+sin(A-B)=2sinAsinB?
Verifying the given expression:
L.H.S
=sin(A+B)+sin(A−B)
=sinAcosB+cosAsinB+sinAcosB−cosAsinB
=sinAcosB+sinAcosB
=2sinAcosB
R.H.S
Hence, L.H.S = R.H.S
If verify that (A + B)′ = A′ + B′