Question

Marco wrote the equation below.

Cos ( -π /2) = cos ( 3π / 2)

Which statement best describes Marcos equation?

Answer 1

Answer:

It is true, because the cosine function has a period of 2π

Step-by-step explanation:

Since, the period of the cos function is 360° ( or 2π radians ), it holds the property of:

$Cos(\theta)=Cos(2\pi +\theta)$

Taking $\theta$ as $-\frac{\pi}{2}$, $(2\pi + \theta)$ is equal to  $2\pi + (-\frac{\pi}{2})\\=2\pi - \frac{\pi}{2}\\=\frac{4\pi-\pi}{2}\\=\frac{3\pi}{2}$

The equation is true!

Note: The cos function is even function

Hence, the equation is true, because the cosine function has a period of 2π, NOT because the cosine function is ODD, which it is not!!