Find the Expression as the Sine or Cosine of an Angle

question 42

Multiple Choice

Find the expression as the sine or cosine of an angle. $$\cos 6 x \cos 3 y + \sin 6 x \sin 3 y$$

• A) \(\cos ( 6 x - 3 y )\)
• B) \(\sin ( 6 x - 3 y )\)
• C) \(\cos ( 6 x + 3 y )\)
• D) \(\sin ( 3 x - 6 y )\)
• E) \(\cos ( 3 x - 6 y )\)