Plotting target points within an n radius plot

I have created a detection range of 20 m radius and essentially created x,y,z points within that range randomly. What I want to be able to do is plot the detection circle, and then plot [detectionx, detectiony, guessz] as a point (maybe a red point) Similar to this (but without the blue points). Any help will be appreciated.

    DetectionRange = 2*pi*(rand(1,1));
    DetectionRadius = 20*sqrt(rand(1,1));
    Detectionx = 20 + DetectionRadius.*cos(DetectionRange); %x coordinate of the dipole is randomly selected somewhere within the radius of 20.
    Detectiony = 20 + DetectionRadius.*sin(DetectionRange); %y coordinate of the dipole is randomly selected somewhere within the radius of 20.
    Guessz = 0;

Answer 1

[Akira Agata]

How about the following solution?

% Data points (N = 10, for example.)
numPoints = 10;
detRange = 2*pi*(rand(numPoints,1));
detRadius = 20*sqrt(rand(numPoints,1));

% Convert to cartesian coordinages
[detX, detY] = pol2cart(detRange,detRadius);

% Show the result
figure
rectangle(...
  'Position',   [-20 -20 40 40],...
  'Curvature',  [1 1],...
  'EdgeColor',  'r')
hold on
scatter(detX,detY,'r^')
daspect([1 1 1])
grid on
box on

[sree chak]

This is brilliant and just what I needed!