## Precalculus (6th Edition)

$f\left( x\right) =\dfrac {\sin x}{x}\Rightarrow$ $f\left( -x\right) =\dfrac {\sin \left( -x\right) }{-x}=\dfrac {-\sin x}{-x}=\dfrac {\sin x}{x}\Rightarrow f\left( x\right) =f\left( -x\right)$ So the equation is even.