Question

Trig:
ODD AND EVEN FUNCTIONS
If cos(x) = -1/3, find cos(-x)
Why is the result -1/3?

Answer 1

we know cos x is an even function

Answer 2

that is f(x) = f(-x) so if cosx = 1/3 then cos(-x) = 1/3 also :)

Answer 3

and it is -1/3 for cos x and cos -x because by the definition of an even funtion