Chapter 7 - Trigonometric Identities and Equations - 7.1 Fundamental Identities - 7.1 Exercises - Page 658: 26

Equation is odd.

$f\left( x\right) =x\cos x\Rightarrow f\left( -x\right) =\left( -x\right) \times \cos \left( -x\right) =\left( -x\right) \times \cos x=-x\cos x\Rightarrow f\left( -x\right) =-f\left( x\right) $ So the equation is odd.