The highlighted in yellow is a mistake, right? I might be going insane.
Where does the PI go?
[tex] \cos(4(t+\pi)) = \cos(4t+4\pi) = \cos(4t) [/tex]
Remember, sin and cos are periodic functions with period 2k*pi, k = integer.
@Office_Shredder: Opps. Nice catch.
@SteamKing: Isn't the period 2pi/k where k is the coefficient of t?
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