[x y]=meshgrid(linspace(-pi,pi,200),linspace(-80,80,200));
colormap(jet(64));
for k=2:49
f=k*(57.15^2)*sin(x)-k*57.15*y+57.15*y.*cos(x)+k;
contour(x,y,f,[k k]);hold on;
end
hold off;
xlabel('x');ylabel('y');
h=colorbar;
set(get(h,'Title'),'string','k');
clear
clc
close all
syms x y
for k=2:0.5:49
ezplot([num2str(k),'*57.15^2*sin(x)-',num2str(k),'*57.15*y+57.15*y*cos(x)=0'])
hold on
end