Question
Find the exact value of the expression.$$\cos 120^{\circ} \cos 30^{\circ}+\sin 120^{\circ} \sin 30^{\circ}$$
Step 1
Step 1: We can use the formula for the cosine of the difference of two angles, which is given by: $$\cos(u - v) = \cos u \cos v + \sin u \sin v$$ Show more…
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