Question

If sin x+sin y=√3(cos y-cos x),prove that sin 3x+sin 3y=0

Answer 1

sin 3x=3sinx-4sin^3 x
sin 3y=3siny-4sin^3 y

so our eqn becomes
3(sinx-sin^3 x+ siny-sin^3 y)(eqn 1)

given,
sinx+siny=√3(cosy-cosx)(eqn 2)
put the value of sinx+siny from eqn 2 in eqn 1

try it.If not able to solve pm.