Answer
$1$
Work Step by Step
Solve. $\cos 12^{\circ} \sin 78^{\circ}+\cos 78^{\circ} \sin 12^{\circ}$
We have
$= \sin (90^{\circ}-12^{\circ}) \sin 78^{\circ}+\cos 78^{\circ} \cos 78^{\circ}$
or, $=\sin^2 78^{\circ}+\cos^2 78^{\circ}$
or, $=1$
