Cosine minus Cosine/Examples

Examples of Use of Cosine minus Cosine

$\cos 20 \degrees$ minus $\cos 50 \degrees$

$\cos 20 \degrees - \cos 50 \degrees = 2 \sin 50 \degrees \cos 10 \degrees$

$\cos 2 A$ minus $\cos 4 A$

$\cos 2 A - \cos 4 A = 2 \sin 3 A \sin A$