Express the function as a trigonometric function of x.
-$\cos 4 x$
A) $\cos ^ { 3 } x - 3 \sin ^ { 2 } x \cos x$
B) $3 \sin x - 4 \sin ^ { 3 } x$
C) $\cos ^ { 4 } x - 6 \sin ^ { 2 } x \cos ^ { 2 } x + \sin ^ { 4 } x$
D) $4 \sin x \cos ^ { 3 } x - 4 \sin ^ { 3 } x \cos x$

Question

Quizplus · Accepted Answer

The correct expression is derived from the double angle formulas and the power-reduction formulas. The correct expression for $\cos 4x$ in terms of trigonometric functions of $x$ is $\cos^4 x - 6 \sin^2 x \cos^2 x + \sin^4 x$, which is derived using these formulas. This matches choice C.

Express the Function as a Trigonometric Function of X cos⁡4x\cos 4 xcos4x

Express the Function as a Trigonometric Function of X $\cos 4 x$