Is the trig function: even, odd, neither $y=cosx$ ?

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Answer 1 · 2015-10-13T18:17:07

It is even since $cos(-x)=cosx AA x in RR$

By definition, $f$ is an odd function if $f(-x)=-f(x)$
$f$ is an even function if $f(-x)=f(x)$

Since $cos(-x) = cosx$ for all $x in RR$ , it implies that $f(x)=cosx$ is an even function.

Is the trig function: even, odd, neither y=cosxy=cosx?