Question
Establish each identity.$\sin \theta[\sin (3 \theta)+\sin (5 \theta)]=\cos \theta[\cos (3 \theta)-\cos (5 \theta)]$
Step 1
The sum-to-product identities are: \[ \sin A + \sin B = 2 \sin \left( \frac{A+B}{2} \right) \cos \left( \frac{A-B}{2} \right) \] \[ \cos A - \cos B = -2 \sin \left( \frac{A+B}{2} \right) \sin \left( \frac{A-B}{2} \right) \] Show more…
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