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alliereid

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**1. Determine an equivalent expression for sin 3x cos x + cos 3x sin x .**

A. 4sin x

B. 2sin x cos x

C. 4sin x cos x

D. 2sin 2x cos 2x

A. 4sin x

B. 2sin x cos x

C. 4sin x cos x

D. 2sin 2x cos 2x

**2. sin(a+b) = sinacosb+cosasinb, sin2x = 2sinxcosx**

3. This question appeared on a practice final I was attempting at. It's on a no calculator section so I'm having difficulty solving it without one. I got up to

sin 3x cos x + cos 3x sin x

= sin(3x + x)

= sin(4x)

The answer is 2sin 2x cos 2x, I know that sin2x = 2sinxcosx but I don't know how to expand it when sin2x becomes sin4x. It'd be great if someone could explain it. Thanks!3. This question appeared on a practice final I was attempting at. It's on a no calculator section so I'm having difficulty solving it without one. I got up to

sin 3x cos x + cos 3x sin x

= sin(3x + x)

= sin(4x)

The answer is 2sin 2x cos 2x, I know that sin2x = 2sinxcosx but I don't know how to expand it when sin2x becomes sin4x. It'd be great if someone could explain it. Thanks!

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