Question

My cousin needs help with this please help thanks

Answer 1

Answer:

A. $\cos \: x - 4 \: \cos \: x \: { \sin}^{2}x$ (first option)

Step-by-step explanation:

➡️ $\cos(x + 2x)$

➡️ $\cos \: x \: { \cos}^{2} x - \sin \: x \: { \sin }^{2} x$

➡️ $\cos \: x(1 - 2 \sin^{2}x) - \sin \: x \times 2 \sin(x) \cos(x)$

➡️ $\cos(x) - 2 \sin^{2} x \cos(x) - 2 \sin^{2} x \cos(x)$

➡️ $\cos(x) - 4 \cos(x) \sin^{2} x$