The given trigonometric equation is,
sinx−siny cosx+cosy =tan x−y 2
Solve left hand side,
L.H.S.= sinx−siny cosx+cosy = [ 2cos( x+y 2 )sin( x−y 2 ) ] [ 2cos( x+y 2 )cos( x−y 2 ) ] = [ sin( x−y 2 ) ] [ cos( x−y 2 ) ] =tan( x−y 2 )
Right hand side is,
R.H.S.=tan( x−y 2 )
Hence, L.H.S.=R.H.S.