Use identities to write the expression as a single function of x or θ.
-$\cos ( \theta - \pi )$
A) $- \sin \theta$
B) $- \cos \theta$
C) $\cos \theta$
D) $\sin \theta$

Question

Quizplus · Accepted Answer

The correct expression is derived using the cosine difference identity, $\cos(\alpha - \beta) = \cos \alpha \cos \beta + \sin \alpha \sin \beta$. Applying this to $\cos(\theta - \pi)$, and knowing that $\cos(\pi) = -1$ and $\sin(\pi) = 0$, we get $\cos \theta \cdot (-1) + \sin \theta \cdot 0 = -\cos \theta$.

Use Identities to Write the Expression as a Single Function cos⁡(θ−π)\cos ( \theta - \pi )cos(θ−π)

Use Identities to Write the Expression as a Single Function $\cos ( \theta - \pi )$