Answers

x<-seq(-2*pi,2*pi,0.05) 
y<-cos(x) 
dat<-data.frame(x=x,y=y) 
plot(dat$x,dat$y,type="l") 
plot(dat$x,dat$y,type="l",lty=4,col="darkgray") 
plot(dat$x,dat$y,type="l",lty="52",col="darkgray")

x<-seq(-10,10,0.1) 
y<-sin(x) 
z<-cos(x) 
matplot(x,cbind(y,z),col=c("red","blue"),las=1,xlab="x",ylab="Sine(x) or Cosine(x)",lty=1:2,type="l")

ll.dat<-Loblolly 
ll.dat$height<-ll.dat$height*0.3048 
summary(ll.dat) 
plot(height~age,type="n",xlab="Age (yr)",ylab="Height (m)",las=1,xlim=c(0,25),data=ll.dat) 
points(ll.dat$age[ll.dat$Seed==307],ll.dat$height[ll.dat$Seed==329],pch=1,col="red",type="o") 
points(ll.dat$age[ll.dat$Seed==311],ll.dat$height[ll.dat$Seed==307],pch=6,col="blue",type="o") 
points(ll.dat$age[ll.dat$Seed==311],ll.dat$height[ll.dat$Seed==311],pch=22,col="black",type="o") 
legend("topleft",legend=c(311,307,329),pch=c(1,6,22),col=c("red","blue","black"))