1. Problem 4-10 in Marion.
with(plots):
f1 :=
dsolve({diff(x(t),t)=y(t),
diff(y(t),t)=-0.05*y(t)-sin(x(t))+0.7*cos(0.1*t),x(0)=0,
y(0)=0},{x(t),y(t)}, type=numeric, output=listprocedure):
odeplot(f1,[t,x(t)],0..100,numpoints=200);
odeplot(f1,[t,x(t)],200..300,numpoints=200);
odeplot(f1,[t,y(t)],0..100,numpoints=200);
odeplot(f1,[t,y(t)],200..300,numpoints=200);
odeplot(f1, [x(t),y(t)],200..300,numpoints=200);
2. Problem 5-2 in Marion.
3. Problem 5-3 in Marion.
4. Problem 5-9 in Marion.