Find the value of $$\cos 120^\circ \cos 240^\circ \cos 180^\circ \cos 60^\circ$$.
$$\cos 120^\circ \cos 240^\circ \cos 180^\circ \cos 60^\circ$$
$$\cos 120^\circ$$=$$\frac{-1}{2}$$
$$\cos 240^\circ$$=$$\frac{-1}{2}$$
 $$\cos 180^\circ$$ = -1
$$\cos 60^\circ$$=$$\frac{1}{2}$$
put the value in equation
$$\cos 120^\circ \cos 240^\circ \cos 180^\circ \cos 60^\circ$$
we get
$$\frac{-1}{8}$$
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