Express the given quantity in terms of sin x or cos x.
-$\cos ( 3 \pi + x )$
A) $- \sin x$
B) $- \cos x$
C) $\cos x$
D) $\sin x - \cos x$

Name: Express the given quantity in terms of sin x or cos x. -$\cos ( 3 \pi + x )$ A) $- \sin x$ B) $- \cos x$ C) $\cos x$ D) $\sin x - \cos x$
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Question

Quizplus · Accepted Answer

Using the angle addition formula for cosine, we have:
$$\cos(3\pi+x)=\cos 3\pi \cos x - \sin 3\pi \sin x=-\cos x$$
Therefore, the answer is choice B, $-\cos x$.

Express the Given Quantity in Terms of Sin X or Cos