% ---------------------------------------------------------------------
% Duas senoides de mesma frequência com fases diferentes (defasagem).
% Requer pgfplots (habilitado via engine.opts na aula).
% ---------------------------------------------------------------------
\begin{tikzpicture}
\begin{axis}[
  width=18cm, height=8.5cm,
  axis lines=middle,
  label style={font=\Large},
  tick label style={font=\Large},
  xlabel={$\omega t$ (rad)}, ylabel={Amplitude},
  xtick={0,90,180,270,360},
  xticklabels={$0$,$\pi/2$,$\pi$,$3\pi/2$,$2\pi$},
  ytick={-1,0,1},
  ymin=-1.4, ymax=1.4,
  xmin=0, xmax=360,
  domain=0:360, samples=200,
  enlargelimits=false,
  legend pos=north east,
  legend style={font=\Large},
  line width=2.2pt,
]
\addplot[blue!70!black, line width=2.4pt] {cos(x+45)};
\addlegendentry{$v_1 = \cos(\omega t + 45^\circ)$}
\addplot[red!70!black, line width=2.4pt, dashed] {cos(x-45)};
\addlegendentry{$v_2 = \cos(\omega t - 45^\circ)$}
\end{axis}
\end{tikzpicture}