q regarding cos being even f(x) (1 Viewer)

[amdspotter]

im confused regarding this
cos2pi/3 would be cos-pi/3
but then if its an even f(x) should it become cospi/3

yh im confused regarding this concept cuz when writing anything in mod arg form i heard that the cos can absorb the negative but then

 

[cossine]

Def even function:
f(x) = f(-x) for all x in the domain.

Theorem:
cos(theta) = cos(-theta) # You can prove this using the unit circle definition cos theta = x

What you have written is

cos(2pi/3) = cos(-pi/3) which does not make sense. because cos(2pi/3) is negative and cos (-pi/3) is positive.

 

[amdspotter]

Def even function:
f(x) = f(-x) for all x in the domain.

Theorem:
cos(theta) = cos(-theta) # You can prove this using the unit circle definition cos theta = x

What you have written is

cos(2pi/3) = cos(-pi/3) which does not make sense. because cos(2pi/3) is negative and cos (-pi/3) is positive.

oh damn yh i understand it now, that cleared all the confusion up