Find the Expression as the Sine or Cosine of an Angle

question 1

Multiple Choice

Find the expression as the sine or cosine of an angle. $$\cos 9 x \cos 8 y + \sin 9 x \sin 8 y$$

• A) \(\cos ( 9 x + 8 y )\)
• B) \(\cos ( 8 x - 9 y )\)
• C) \(\cos ( 9 x - 8 y )\)
• D) \(\sin ( 9 x - 8 y )\)
• E) \(\sin ( 8 x - 9 y )\)

Understand the impacts of nutrient pollution on aquatic ecosystems.

Explain the process and importance of sewage treatment.

Recognize the differences between point source and nonpoint source pollution.

Assess the effectiveness of current pollution control measures.

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