Verify That the Equation Is an Identity $y = 4 ( \cos 2 \pi x \cos b t + \sin 2 \pi x \sin b t )$

question 234

Multiple Choice

Verify that the equation is an identity.
-A vibrating wire has a vertical displacement given by $y = 4 ( \cos 2 \pi x \cos b t + \sin 2 \pi x \sin b t )$ . Assume $\mathrm { b }$ and $\mathrm { t }$ are constants. Write $\mathrm { y }$ as a cosine function of $\mathrm { x }$ .

• A) \(y = 8 \cos ( 2 \pi x + b t )\)
• B) \(y = 4 \cos ( 2 \pi x - b t )\)
• C) \(y = \cos ( 2 \pi x - b t )\)
• D) \(y = 4 \cos ( 2 \pi x + b t )\)

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