Product to Sum and Sum to Product Formulas Worksheet with Answer Key

What's on the worksheet

1. Write each product as a sum or difference with no products of trig functions left.
2. Find the exact value of each product.
   4\sin 97.5^\circ\sin 52.5^\circ\cos 105^\circ\sin 15^\circ\cos\dfrac{11\pi}{12}\cos\dfrac{5\pi}{12}
3. Write each sum or difference as a product.
   \sin\dfrac{5x}{2} - \sin\dfrac{x}{2}\cos(x + h) - \cos x\sin 3x + \cos x\sin 105^\circ - \sin 15^\circ
4. Mateo is tuning a piano.
5. Find the exact value of 20^ 40^ 80^.