Using the trigonometric identity $\cos (A-B) = \cos A \cos B + \sin A \sin B$, we can simplify the expression:
$\cos(107^\circ - 17^\circ) = \cos 107^\circ \cos 17^\circ + \sin 107^\circ \sin 17^\circ$
$\cos 90^\circ = \cos 107^\circ \cos 17^\circ + \sin 107^\circ \sin 17^\circ$
$0 = \cos 107^\circ \cos 17^\circ + \sin 107^\circ \sin 17^\circ$
Therefore, the expression $\cos 107^\circ \cos 17^\circ + \sin 107^\circ \sin 17^\circ$ simplifies to 0.
Using the trigonometric identity $\cos (A-B) = \cos A \cos B + \sin A \sin B$, we can simplify the expression:
$\cos(107^\circ - 17^\circ) = \cos 107^\circ \cos 17^\circ + \sin 107^\circ \sin 17^\circ$
$\cos 90^\circ = \cos 107^\circ \cos 17^\circ + \sin 107^\circ \sin 17^\circ$
$0 = \cos 107^\circ \cos 17^\circ + \sin 107^\circ \sin 17^\circ$
Therefore, the expression $\cos 107^\circ \cos 17^\circ + \sin 107^\circ \sin 17^\circ$ simplifies to 0.