Which statement regarding the function y=cos (x) is true?

A. The cosine function is odd, so it is symmetrical across the origin.

B. cos (x) = cos (-x)

C. - cos (x) = cos (x

D. Since the cosine function is eevn, reflection across the x-axis does not change the graph.

Hints:

use the calculator to check if any of the options are correct. Try x=pi/6 (or 30 degrees).

Odd functions satisfy the property

f (x) = - f (-x)

For this reason, odd functions are symmetrical about the origin.

Examples of odd functions: sin (x), x^3, x+3x^5, tan (x), sin (x) * cos (x), x*sin (x)

(use your calculator to check that the above are true).

Even functions satisfy the property

f (x) = f (-x)

Even functions are symmetrical about the y-axis.

Examples: x^2, cos (x), x^4+2, |x|, sin^2 (x), x^2*cos (x)

There are functions that are neither odd nor even,

examples:

x^2+4x+3, sin (x) + cos (x)