Express each of the following as a product.

1. sin 10x + sin 6x

2. sin 7x – sin 3x

3. cos 7x + cos 5x

4. cos2x – cos 4x

1. = 2

=2

=2

Using,

sin( A +B)= sinA cos B + cosA sinB

= 2

= 2

= 2cos5x sin2x

Using,

sin( A - B)= sinA cos B - cosA sinB

= 2

= 2

= 2

Using,

cos (A + B) = cosAcosB – sinAsinB

4.= -2

= -2

= 2sin3x sinx

Using,

cos (A - B) = cosAcosB+ sinAsinB