Use an identity to write the expression as a single trigonometric function or as a single number.
-$2 \cos ^ { 2 } 4 x - 1$
A) $\frac { 1 } { 2 } \sin 16 x$
B) $\cos 8 x$
C) $\cos 4 x$
D) $2 \sin 4 x$

Question

Quizplus · Accepted Answer

This expression can be simplified using the double angle identity for cosine, which states that $\cos(2\theta) = 2\cos^2(\theta) - 1$. By setting $2\theta = 8x$, we find that $2\cos^2(4x) - 1 = \cos(8x)$.

Use an Identity to Write the Expression as a Single 2cos⁡24x−12 \cos ^ { 2 } 4 x - 12cos24x−1

Use an Identity to Write the Expression as a Single $2 \cos ^ { 2 } 4 x - 1$