x^2 + y^2 =9

I want to plot the above equation in matlab but i dont know how to plot please help or provide me code

Answer 1

[Dimitris Kalogiros]

This equation depicts a circle with radious 3.

clc; clearvars;

syms   x y

eq= x^2+y^2==9

fimplicit(eq, [-3 3]);
xlabel('x'); ylabel('y');
ax=gca;
ax.YAxisLocation='origin';  ax.XAxisLocation='origin' ;
ax.XLim=[-5 5]; ax.YLim=[-5 5];

In case you are not familiar with symbolic math toolbox, you can use the following

clc; clearvars;

ci=@(x,y) x.^2+y.^2-9;
fimplicit(ci, [-3 3 -3 3]);

xlabel('x'); ylabel('y');
ax=gca;
ax.YAxisLocation='origin';  ax.XAxisLocation='origin' ;
ax.XLim=[-5 5]; ax.YLim=[-5 5];

Answer 2

[Image Analyst]

viscircles([0,0], 3); % Plot circle centered at (0,0) and with radius 3
grid on; % Show gridlines
axis square % Make sure it's square and not elliptical by making x and y scale the same