The correct answer is C.
StartFraction sine theta plus sine 7 theta Over sine theta minus sine 7 theta EndFraction equals StartStartFraction negative 2 sine StartFraction theta plus 7 theta Over 2 EndFraction cosine StartFraction theta minus 7 theta Over 2 EndFraction OverOver 2 sine StartFraction theta minus 7 theta Over 2 EndFraction cosine StartFraction theta plus 7 theta Over 2 EndFraction EndEndFraction equals negative StartFraction tangent left parenthesis 4 theta right parenthesis Over tangent 3 theta EndFraction