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Magazine Problem 176
Rewrite the sum or difference as a product. $$\cos (3 x)+\cos (9 x)$$
Problem 177
Rewrite the sum or difference as a product. $$\sin h-\sin (3 h)$$
Problem 178
Evaluate the product for the following using a sum or difference of two functions. Evaluate exactly. $$\cos \left(45^{\circ}\right) \cos \left(15^{\circ}\right)$$
Problem 179
Evaluate the product for the following using a sum or difference of two functions. Evaluate exactly. $$\cos \left(45^{\circ}\right) \sin \left(15^{\circ}\right)$$
Problem 180
Evaluate the product for the following using a sum or difference of two functions. Evaluate exactly. $$\sin \left(-345^{\circ}\right) \sin \left(-15^{\circ}\right)$$
Problem 181
Evaluate the product for the following using a sum or difference of two functions. Evaluate exactly. $$\sin \left(195^{\circ}\right) \cos \left(15^{\circ}\right)$$
Problem 182
Evaluate the product for the following using a sum or difference of two functions. Evaluate exactly. $$\sin \left(-45^{\circ}\right) \sin \left(-15^{\circ}\right)$$
Problem 184
Evaluate the product using a sum or difference of two functions. Leave in terms of sine and cosine. $$2 \sin \left(100^{\circ}\right) \sin \left(20^{\circ}\right)$$
Problem 185
Evaluate the product using a sum or difference of two functions. Leave in terms of sine and cosine. $$2 \sin \left(-100^{\circ}\right) \sin \left(-20^{\circ}\right)$$
Problem 186
Evaluate the product using a sum or difference of two functions. Leave in terms of sine and cosine. $$\sin \left(213^{\circ}\right) \cos \left(8^{\circ}\right)$$
