What is \[\cos 20{}^\circ +\cos 100{}^\circ +\cos 140{}^\circ \] equal to?

What is \[\cos 20{}^\circ +\cos 100{}^\circ +\cos 140{}^\circ \] equal

1.	What is \[\cos 20{}^\circ +\cos 100{}^\circ +\cos 140{}^\circ \] equal to?
A.	2
B.	1
C.	\[1/2\]
D.	0
Answer» E.

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What is \[\cos 20{}^\circ +\cos 100{}^\circ +\cos 140{}^\circ \] equal to?

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