function picture(p,q,x)
%plots the curves p and q
t=linspace(0,2*pi);%parameter values
P=feval(p,t);%evaluate the values of p
Q=feval(q,t);%evaluate the values of q
plot(P(1,:),P(2,:),'r')
plot(Q(1,:),Q(2,:),'g')
A=feval(p,x(1));%a point on p
B=feval(q,x(2));%a point on q
plot([A(1),B(1)],[A(2),B(2)],'k')