ClearAll; 
plotsin = Plot[Sin[t],{t,0,2 Pi},PlotPoints->100,
				PlotRange->{{0,2 Pi},{-1.02,1.02}},
				AxesOrigin->{-0.25,-1.1},
				AxesLabel->{"t","y"},
				PlotLabel->"(a) y = S(t)"];
plotcos = Plot[Cos[t],{t,0,2 Pi},PlotPoints->100,
				PlotRange->{{0,2 Pi},{-1.02,1.02}},
				AxesOrigin->{-0.25,-1.1},
				AxesLabel->{"t","y"},
				PlotLabel->"(b) y = C(t)"];
Show[GraphicsArray[{{plotsin},{plotcos}}],PlotLabel->"Figure 23.3"]